Didn’t post it yesterday because my Internet connection was not working.
But because you figure out wonderful things —
Why, when the greatest power of the Sun
is reputed to be twice-nine times greater
than that of the terrestrial orb,
does he not overwhelm the terrestrial cones
Take up the reckoning work of reason.
On the other hand, gaze upon Phoebus
who travels through the sublime vaults of the world
and may illuminate every lowly land
from his high passages.
This is remarkable however one may touch on it:
in that whether he should have strewn his fires
or have beamed them on a slanting axis,
they are crushed at the Earth’s radius.
The rest of the lights of the Sun,
by which radiant darts he becomes more visible,
spread through the vast voids
unhindered by the [Earth’s] globe
as long as the pyramid’s peak may complete
its residing shadow.
By which neighbors’ shadows,
when damp Phoebe drives her icy yoked team
deepest through them, sometimes
she is discolored.
She misses her absent brother,
and lacks her bloodless face.
But why is only the Moon plundered of light?
Indeed, it is not wonderful.
Of course another light warms
those needing her light;
for when the nearest part of the cone begrudges it,
she badly hopes for the sky rays of her brother.
But the remaining choir of stars
is not touched by shadows,
and their brightness is their own,
nor are they reddened by the Sun.
Yet rush up to the lofty astral rays
far beyond the Sun; clear and bright,
it is dragged off,
attached to the vertex of the sky.
Besides, why would it not always be paled
by the orb every six months?
The curved passages come around
by a slanting track.
On the other hand, when by wandering,
the curved thing amasses twisted deviations
from what is fixed, the sun leaves the cone
beyond reach, and twists the robe of night,
and shines upon his sister.
These things are the reason for it:
where the red-gold brightness of the august Sun
is crushed by sudden shadows, lacking light,
Luna passes between Earth and Sun
with the nourishing wheel of her body,
protecting her brother from straight obstructions.
I’m not as sure about the translation of this part of the poem. I also haven’t read “De Natura Rerum,” so I’m not sure if St. Isidore touched on any of these topics. There are also various terms used for “curved” which have different connotations. So I’m not sure I get this entirely, although obviously Sisibut is inquiring about orbital mechanics, and why we can see anything at all during lunar eclipses at night.
The king and the bishop had sort of a frenemy relationship. Part was because Sisibut believed in just ordering his still-Arian Visigoths, and the local population of Spanish Jews, to convert or be forced. (Standard for your barbarian king, but not appreciated in a guy who presumably should know better. Sisibut didn’t get any sainthood attributions.) Part was because Sisibut was learned enough to fund Isidore’s book projects, and then to write reviews of them with his own sharp questions.
(When you are Isidore of Seville and probably the most learned man in Europe (except for your dead brother and the dead pope, Gregory the Great), you may have just a tad bit of alpha male pride to lose.)
Anyway, it’s a bit fun to see Sisibut alternating between scientific principles of astronomy and poetic conventions drawn from mythology. The Sun is Phoebus (Apollo), the Moon is his sister Phoebe (another name for Artemis as Selene). The chariot of Phoebe’s Moon is drawn by a team of pure white animals (Sisibut doesn’t make a choice between deer, crescent-horned oxen, or horses, just calling them “gelidos”). The Earth is Tellus.