Astronomical Lore in Chaucer Part 4

Chaucer briefly describes the crescent moon by calling her

"The bente mone with hir hornes pale."[99]

In Troilus' prayer to the moon, the line

"'I saugh thyn hornes olde eek by the morwe,'"[100]

is practically the only one in which Chaucer gives any hint of the times at which the moon in her various phases may be seen. The phase of the 'new moon,' when the moon is in conjunction with the sun (i. e., between the earth and the sun, so that we cannot see the illuminated hemisphere of the moon) is mentioned in the same poem:

"Right sone upon the chaunging of the mone, Whan lightles is the world a night or tweyne."[101]

There is a very definite description of three of the moon's phases in the following pa.s.sage from _Boethius_:[102] "so that the mone som-tyme shyning with hir ful hornes, meting with alle the bemes of the sonne hir brother, hydeth the sterres that ben lesse; and som-tyme, whan the mone, pale with hir derke hornes, approcheth the sonne, leseth hir lightes;" The moon 's.h.i.+ning with her full horns' means with her horns filled up as at full moon when she is in a position opposite both earth and sun so that she reflects upon the earth all the rays of the sun. The moon "with derke hornes" refers of course to the waning moon, a thin crescent near the sun and almost obscured in his light, which approaching nearer the sun is entirely lost to our view in his rays and becomes the new moon.

Chaucer's most interesting references to the moon are found in the prayer of Aurelius to the sun in the _Frankeleyns Tale_. Dorigen has jestingly promised to have pity on Aurelius as soon as he shall remove all the rocks from along the coast of Brittany, and Aurelius prays to the sun, or Apollo, to help him by enlisting the aid of the moon, in accomplis.h.i.+ng this feat. The sun's sister, Lucina, or the moon, is chief G.o.ddess of the sea; just as she desires to follow the sun and be quickened and illuminated by him, so the sea desires to follow her:

"'Your blisful suster, Lucina the shene, That of the see is chief G.o.ddesse and quene, Though Neptunus have deitee in the see, Yet emperesse aboven him is she: Ye knowen wel, lord, that right as hir desyr Is to be quiked and lightned of your fyr, For which she folweth yow ful bisily, Right so the see desyreth naturelly To folwen hir, as she that is G.o.ddesse Bothe in the see and riveres more and lesse.'"[103]

In calling Lucina chief G.o.ddess of the sea and speaking of the sea's desire to follow her, Chaucer is, of course alluding to the moon's effect upon the tides; and in the line:

"'Is to be quiked and lightned of your fyr,'"

the reference is to the fact that the moon derives her light from the sun.

Instead of leaving it to the sun-G.o.d to find a way of removing the rocks for him, Aurelius proceeds to give explicit instructions as to how this may be accomplished. As the highest tides occur when the moon is in opposition or in conjunction with the sun, if the moon could only be kept in either of these positions with regard to the sun for a long enough time, so great a flood would be produced, Aurelius thinks, that the rocks would be washed away. So he prays Phebus to induce the moon to slacken her speed at her next opposition in Leo and for two years to traverse her sphere with the same (apparent) velocity as that of the sun, thus remaining in opposition with him:

"'Wherfore, lord Phebus, this is my requeste-- Do this miracle, or do myn herte breste-- That now, next at this opposicioun, Which in the signe shal be of the Leoun, As preyeth hir so greet a flood to bringe, That fyve fadme at the leeste it overspringe The hyeste rokke in Armorik Briteyne; And lat this flood endure yeres tweyne; . . . . . . . . .

Preye hir she go no faster cours than ye, I seye, preyeth your suster that she go No faster cours than ye thise yeres two.

Than shal she been evene atte fulle alway, And spring-flood laste bothe night and day.'"[104]

References to eclipses of the moon occur seldom in Chaucer. In the second part of the _Romaunt of the Rose_, which is included in complete editions of Chaucer's works but which he almost certainly did not write, there is a description of a lunar eclipse and of its causes. Fickleness in love is compared to an eclipse:

"For it shal chaungen wonder sone, And take eclips right as the mone, Whan she is from us (y)-let Thurgh erthe, that bitwixe is set The sonne and hir, as it may falle, Be it in party, or in alle; The shadowe maketh her bemis merke, And hir hornes to shewe derke, That part where she hath lost hir lyght Of Phebus fully, and the sight; Til, whan the shadowe is overpast, She is enlumined ageyn as faste, Thurgh brightnesse of the sonne bemes That yeveth to hir ageyn hir lemes."[105]

This pa.s.sage is so clear that it needs no explanation.

An eclipse of the moon, since it is caused by the pa.s.sing of the moon into the shadow of the earth, can only take place when the moon is full, that is, in _opposition_ to the sun. This fact is suggested in a reference in _Boethius_ to a lunar eclipse:

"the hornes of the fulle mone wexen pale and infect by the boundes of the derke night;"[106]

In the next lines Chaucer mentions the fact that the stars which are lost to sight in the bright rays of the full moon become visible during an eclipse:

"and ... the mone, derk and confuse, discovereth the sterres that she hadde y-covered by hir clere visage."[107]

3. _The Planets_

All the planets that are easily visible to the unaided eye were known in Chaucer's time and are mentioned in his writings, some of them many times.

These planets are Mercury, Venus, Mars, Jupiter, and Saturn. According to the Ptolemaic system, which as we have seen, held sway in the world of learning during Chaucer's century, the sun and moon were also held to be planets, and all were supposed to revolve around the earth in concentric rings, the moon being nearest the earth, and the sun between Venus and Mars. The circular orbit of each planet was called its "deferent" and upon the deferent moved, not the planet itself, but an imaginary planet, represented by a point. The real planet moved upon a smaller circle called the "epicycle" whose center was the moving point representing the imaginary planet. The deferent of each planet was supposed to be traced as a great circle upon a transparent separate crystal sphere; and all of the crystal spheres revolved once a day around an axis pa.s.sing through the poles of the heavens. As the sun and moon did not show the same irregularities[108] of motion as the planets, Ptolemy supposed these two bodies to have deferents but no epicycles. Later investigators complicated the system by adding further secondary imaginary planets, revolving in Ptolemy's epicycles and with the actual planets attached to additional corresponding epicycles. They even supposed the moon to have one, perhaps two epicycles and we shall find this notion reflected in Chaucer. The eighth sphere had neither deferent nor epicycle but to it were attached the fixed stars. This sphere as we have seen earlier, revolved slowly from west to east to account for the precession of the equinoxes, while a ninth sphere, the _primum mobile_, imparted to all the inner spheres their diurnal motion from east to west.

Chaucer's poetical references to the planets, as we have found to be true in the case of the sun and moon, do not give us satisfactory evidence of the extent of his knowledge, but occasional pa.s.sages from his prose works again throw light on these allusions. Chaucer refers to the planets in general as 'the seven stars,' as, for instance, in the lines:

"And with hir heed she touched hevene, Ther as shynen sterres sevene."[109]

and

"To have mo floures, swiche seven As in the welken sterres be."[110]

Chaucer was undoubtedly familiar with the irregularities of the planetary movements, and with the theory of epicycles by which these irregular movements were in his day explained, although it is not from his poetry that we can learn the fact. He uses the word 'epicycle' only once in all his works. In the _Astrolabe_ when comparing the moon's motion with that of the other planets, he says: "for sothly, the mone moeveth the contrarie from othere planetes as in hir episicle, but in non other manere."[111]

In the _Astrolabe_[112] Chaucer explains a method of determining whether a planet's motion is retrograde or direct.[113] The alt.i.tude of the planet and of any fixed star, is taken, and several nights later at the time when the fixed star has the same alt.i.tude as at the previous observation, the planet's alt.i.tude is again observed. If the planet is on the right or east side of the meridian, and its second alt.i.tude is less than its first, then the planet's motion is direct. If the planet is on the left or west side of the meridian, and has a smaller alt.i.tude at the second observation than at the first, then the planet's motion is retrograde. If the planet is on the east side of the meridional line when its alt.i.tude is taken and the second alt.i.tude is greater than the first, it is retrograde; and if it is on the west side and its second alt.i.tude is greater, it is direct. This method would be correct were it not that a change in the planet's declination or angular distance from the celestial equator might render the conclusions incorrect.

Chaucer mentions the irregularity of planetary movements in _Boethius_ also when he says: "and whiche sterre in hevene useth wandering recourses, y-flit by dyverse speres."[114] The expression "y-flit by dyverse speres"

may have reference only to the one motion of the planets, that is, their motion concentric to the star-sphere; or it may be used to include also their epicyclic motion. Skeat interprets the expression in the former way; but the context, it seems, would justify interpreting the words "dyverse speres" as meaning the various spheres of the planets to-gether with their epicycles; i. e., both deferents and epicycles.

Of all the planets, that most often mentioned by Chaucer is Venus, partly, no doubt, because of her greater brilliance, but probably in the main because of her greater astrological importance; for few of Chaucer's references to Venus, or to any other planet, indeed, are without astrological significance. Chaucer refers to Venus, in the cla.s.sical manner, as Hesperus when she appears as evening[115] star and as Lucifer when she is seen as the morning star: "and that the eve-sterre Hesperus, which that in the firste tyme of the night bringeth forth hir colde arysinges, cometh eft ayein hir used cours, and is pale _by the morwe_ at the rysing of the sonne, and is thanne cleped Lucifer."[116] Her appearance as morning star is again mentioned in the same work: "and after that Lucifer the day-sterre hath chased awey the derke night, the day the fairere ledeth the rosene hors _of the sonne_,"[117] and in _Troilus and Criseyde_ where it is said that

"Lucifer, the dayes messager, Gan for to ryse, and out hir bemes throwe;"[118]

Elsewhere in the same poem her appearance as evening star is mentioned but she is not this time called Hesperus:

"The brighte Venus folwede and ay taughte The wey, ther brode Phebus doun alighte;"[119]

Occasionally Venus is called Cytherea, from the island near which Greek myth represented her as having arisen from the sea. Thus in the _Knightes Tale_:

"He roos, to wenden on his pilgrimage Un-to the blisful Citherea benigne, I mene Venus, honurable and digne."[120]

and in the _Parlement of Foules_;

"Citherea! thou blisful lady swete,"[121]

The relative positions of the different planets in the heavens is suggested by allusions to the different sizes of their spheres and to their different velocities. In the _Compleynt of Mars_ the comparative sizes and velocities of the spheres of Mercury, Venus and Mars are made the basis for most of the action of the poem. The greater the sphere or orbit of a planet, the slower is its apparent motion. Thus Mars in his large sphere moves about half as fast as Venus and in the poem it is planned that when Mars reaches the next palace[122] of Venus, he shall by virtue of his slower motion, wait for her to overtake him:

"That Mars shal entre, as faste as he may glyde, Into hir nexte paleys, to abyde, Walking his cours til she had him a-take, And he preyde hir to haste hir for his sake."[123]

Venus in compa.s.sion for his solitude hastens to overtake her knight:

"She hath so gret compa.s.sion of hir knight, That dwelleth in solitude til she come; . . . . . . . . .

Wherefore she spedde hir as faste in her weye, Almost in oon day, as he dide in tweye."[124]

When Phebus comes into the palace with his fiery torch, Mars will not flee and cannot hide, so he girds himself with sword and armour and bids Venus flee. Phebus, who in Chaucer's time was regarded as the fourth planet, can overtake Mars but not Venus because his sphere is between theirs and his motion is consequently slower than that of Venus but faster than that of Mars:

"Flee wolde he not, ne mighte him-selven hyde.

He throweth on his helm of huge wighte, And girt him with his swerde; and in his honde His mighty spere, as he was wont to fighte, He shaketh so that almost it to-wonde; Ful hevy he was to walken over londe; He may not holde with Venus companye, But bad hir fleen, lest Phebus hir espye.

"O woful Mars! alas! what mayst thou seyn, That in the paleys of thy disturbaunce Art left behinde, in peril to be sleyn?

That thou nere swift, wel mayst thou wepe and cryen."[125]