James Russell Lowell, Among my books

[71] (Inferno), or directly by a righteous employment of it (Purgatorio), to the same end. The use of the sciences is to induce in us the ultimate perfection, that of speculating upon truth; the use of the highest of them, theology, the contemplation of God.¹ To this they all lead up. In one of those curious chapters of the Convito,² where he points out the analogy between the sciences and the heavens, Dante tells us that he compares moral philosophy with the crystalline heaven or Primum Mobile, because it communicates life and gives motion to all the others below it. But what gives motion to the crystalline heaven (moral philosophy) itself ‘The most fervent appetite which it has in each of its parts to be conjoined with each part of that most divine quiet heaven’ (Theology).³ Theology, the divine science, corresponds with the Empyrean, ‘because of its peace, the which, through the most excellent certainty of its subject, which is God, suffers no strife of opinions or sophistic arguments.’⁴ No one of the heavens is at rest but this, and in none of the inferior sciences can we find repose, though he likens physics to the heaven of the fixed stars, in whose name is a suggestion of the certitude to be arrived at in things demonstrable. Dante had this comparison in mind, it may be inferred, when he said,

Well I perceive that never sated is
Our intellect unless the Truth illume it
Beyond which nothing true⁵ expands itself.
It rests therein as wild beast in his lair;