[154] “As the Philosopher says at the beginning of the _First Philosophy_, ‘All men naturally desire to have knowledge.’ The reason of this may be that everything, being impelled by foresight belonging to its own nature, tends to seek its own perfection. Wherefore inasmuch as knowledge is the final perfection of our soul in which our final happiness consists, all men are naturally subject to the desire for it.” _Conv._ I. i. 1-11. ------------------------------------------------------------------------ And from a study of the _Convivio_ we may learn much of the authors most esteemed, the methods of study pursued, and the results obtained, by thirteenth-century scholars seeking to gain the ultimate perfection of the soul. Astronomy is frequently introduced, especially in the second and third treatises. The Ode which forms the text of the second treatise is that which is quoted by Charles of Hungary in _Par._ viii. 37—“Voi che intendendo il terzo ciel movete,”[155] and it gives Dante the occasion to speak first of the heaven of Venus, explaining Ptolemy’s system of epicycles, and later of all the heavens in their order, and the celestial bodies contained in them. The ode of the third treatise contains the line “Non vede il Sol, che tutto il mondo gira ...”[156] and upon this he hangs a complete little essay describing the movements of the sun, and how they appear from different parts of the earth, as well as a short dissertation on the question whether it is Sun or Earth which actually moves. ------------------------------------------------------------------------ [155] “Oh ye whose intellectual ministry Moves the third heaven.”—_Carey._ [156] “The sun sees not, though circling all the world.” ------------------------------------------------------------------------