Synesius, Dio, 15

[15] [1160] Now Pythagoras, or any disciple and supporter of Pythagoras, will say, since his utterances have the force of laws, that the independent mind is best fitted by nature for any vocation, that is to say, a mind which by its energy is actually a poetical and rhetorical force, even if not the most highly endowed for everything. Certain men of this caliber have come here in the past endowed with greatness, or an intimate acquaintance with knowledge, men who needed no teaching, for they were themselves examples of proficiency. The great majority, however, have had no such share in this good fortune; some of them are hopelessly deficient. But possessing a certain power of understanding, some more, some less, some near to the end in view, and some far from it, they are brought to this point by active minds, these minds being the creation of their own activity. Our whole devotion to literature has this one aim in view, namely, the summoning of our forces to activity. Let this employment from the beginning therefore invoke everywhere the help of letters as our guide, and let it be fixed steadily upon the perception of their meaning and, as it advances, let it make trial of its own strength and not entirely cling to the syllables.

For just as any other problem becomes a source of satisfaction to us if our perplexity over it exercises our invention; thus also the mind, compelled to weave that which is missing into the sequence of what is read, and not resting entirely on vision, makes practice in venturing upon a similar work by itself. At the same time it accustoms itself not to belong to others but to itself, for these books containing errors seem to seek out the mind that is superior to mere eyesight.