Testing Theology With Optics: PARADISO, Canto II, Lines 85 - 105

Beatrice continues in her scientific and Scholastic explanation for moon spots by taking apart a secondary argument . . . and proposing an optical experiment.

She voices an objection Dante might have: perhaps there are dense bits behind the rare bits that reflect light as darker spots because those denser bits are farther off.

To prove him wrong (although he hasn't said a thing), she asks him to set up an experiment with three mirrors.

Problem is, he doesn't need three mirrors for this experiment. But he does need three if he wants to show that the universe is based on a trinitarian concept of God.

The segments for this episode of WALKING WITH DANTE:

[01:13] My English translation of PARADISO, Canto II, Lines 85 - 105. To read along or to continue the conversation with me, scroll down this page.

[03:25] The basic structure of the passage: Beatrice's secondary explanation (or objection), then her experimental refutation of that explanation.

[05:29] Medieval optical theory and its limits.

[08:36] The limits of Beatrice's proposed experiment--and why they may not matter since the point may be theology, not optical theory or cosmology.

[17:23] Four possiblereasons this long discussion of moon spots lands here in COMEDY.

[23:41] Rereading the passage: PARADISO, Canto II, lines 85 - 105.

My English translation of PARADISO, Canto II, Lines 85 - 105:

[Beatrice continued:] “If it’s such that this rare stuff doesn’t stretch fully through [the moon],

There must be an end point at which

Its [dense] opposite wouldn’t let much [light] pass through—

“So a ray must bounce back from there,

Just as color comes back from a glass

That has lead hidden underneath.

“Now you’ll say that the ray shows darker

There than in other parts

Because it’s reflected from farther back.

“When it comes to this objection,

An experiment can set you free, if you’ll ever try it,

Since [experimentation] is the fountain for the rivers of all your arts.

“Take three mirrors and place two

Equidistant from you, so that the remaining one, more removed,

Can find your eyes from between [the other two].

“Thus turned toward them, make a light behind you

Shine on the three mirrors so that

It returns a reflection to you from all three.

“Well it is that the light farther off extends

Smaller in [its] size, yet you’ll see

Its appearance as an equal brightness. . . .”