Chaucer's treatment of astronomical lore in his poetry differs much from
his use of it in his prose writings. In poetical allusions to heavenly
phenomena, much attention to detail and a pedantic regard for accuracy
would be inappropriate. References to astronomy in Chaucer's poetry are,
as a rule rather brief, specific but not technical, often purely
conventional but always truly poetic. There are, indeed, occasional
passages in Chaucer's poetry showing so detailed a knowledge of
observational[50] astronomy that they would seem astonishing and, to many
people, out of place, in modern poetry. They were not so in Chaucer's
time, when the exigencies of practical life demanded of the ordinary man a
knowledge of astronomy far surpassing that possessed by most of our
contemporaries. Harry Bailly in the _Introduction to the Man of Lawes
Tale_ determines the day of the month and hour of the day by making
calculations from the observed position of the sun in the sky, and from
the length of shadows, although, says Chaucer, "he were not depe expert in
lore."[51] Such references to technical details of astronomy as we find
in this passage are, however, not common in Chaucer's poetry; in his
_Treatise on the Astrolabe_, on the other hand, a professedly scientific
work designed to instruct his young son Louis in those elements of
astronomy and astrology that were necessary for learning the use of the
astrolabe, we have sufficient evidence that he was thoroughly familiar
with the technical details of the astronomical science of his day.
In Chaucer's poetry the astronomical references employed are almost wholly
of two kinds: references showing the time of day or season of the year at
which the events narrated are supposed to take place; and figurative
allusions for purposes of illustration or comparison. Figurative uses of
astronomy in Chaucer vary from simple similes as in the _Prologue to the
Canterbury Tales_, where the friar's eyes are compared to twinkling
stars[52] to extended allegories like the _Compleynt of Mars_ in which the
myth of Venus and Mars is related by describing the motions of the planets
Venus and Mars for a certain period during which Venus overtakes Mars,
they are in conjunction[53] for a short time, and then Venus because of
her greater apparent velocity leaves Mars behind. One of the most
magnificent astronomical figures employed by Chaucer is in the _Hous of
Fame_. Chaucer looks up into the heavens and sees a great golden eagle
near the sun, a sight so splendid that men could never have beheld its
equal 'unless the heaven had won another sun:'
"Hit was of golde, and shone so bright,
That never saw men such a sighte,
But-if the heven hadde y-wonne
Al newe of golde another sonne;
So shoon the egles fethres brighte,
And somwhat dounward gan hit lighte."[54]
Besides mentioning the heavenly bodies in time references and figurative
allusions, Chaucer also employs them often in descriptions of day and
night, of dawn and twilight, and of the seasons. It is with a poet's joy
in the warm spring sun that he writes:
"Bright was the day, and blew the firmament,
Phebus of gold his stremes doun hath sent,
To gladen every flour with his warmnesse."[55]
and with a poet's delight in the new life and vigor that nature puts forth
when spring comes that he writes the lines:
"Forgeten had the erthe his pore estat
Of winter, that him naked made and mat,
And with his swerd of cold so sore greved;
Now hath the atempre sonne al that releved
That naked was, and clad hit new agayn."[56]
Chaucer's astronomical allusions, then, except in the _Treatise on the
Astrolabe_ and in his translation of _Boethius de Consolatione
Philosophiae_, in which a philosophical interest in celestial phenomena is
displayed, are almost invariably employed with poetic purpose. These
poetical allusions to heavenly phenomena, however, together with the more
technical and detailed references in Chaucer's prose works give evidence
of a rather extensive knowledge of astronomy. With all of the important
observed movements of the heavenly bodies he was perfectly familiar and it
is rather remarkable how many of these he uses in his poetry without
giving one the feeling that he is airing his knowledge.