We seek out instead all the auxiliaries that can maintain our thought in the state of attention.
Omnia potius adjumenta perquirimus, quibus cogitatio nostra retineatur attenta.
In the first part of the Discours de la méthode Descartes narrates the quest of a young man for assurance, both in the judgments of his intellectual life, and in the more practical moral affairs of existence: "I always had an intense desire to learn to distinguish truth from falsehood in order to see clearly in my actions and to walk with assurance in this life" ("J'avais toujours un extrême dU+0E9sir d'apprendre à distinguer le vrai d'avec le faux, pour voir clair en mes actions, et marcher avec assurance en cette vie" [ 1:577]). However, he found only disappointment in his studies. Instead of teaching him to distinguish truth from error, philosophy furnished only a welter of opinions that could be established as likely but not as certain; it was not a monument to truth, but to the vanity of philosophers and to their skill as dialecticians. Mathematics alone gave him some measure of satisfaction because of the certainty and self-evidence of its proofs, but he was later to realize that as a student he had scarcely recognized its potential application. When he turned from libraries to the great book of the world, his travels were hardly more reassuring; the diversity of customs among the peoples he visited paralleled the Babel of opinions among philosophers. Assurance, he discovered, was not to be found in the erudition of scholars any more