History of Greek and Roman philosophy
Edited by Vincenzo Cicero, introduction by Maria Bettetini
Here too, the Greeks have been and remain masters: one is a philosopher only if and as long as one is totally free, that is, only if and as long as, in absolute freedom, one contemplates or searches for the true as such, without further predetermined reasons. By knowing, in an unbiased way, man approaches the truth, and, in this way, fulfills his rational nature to the highest degree, and consequently achieves happiness.