Plato
If I were again beginning my studies, I would follow the advice of Plato and start with mathematics.
Nothing can be more absurd than the practice that prevails in our country of men and women not following the same pursuits with all their strengths and with one mind, for thus, the state instead of being whole is reduced to half.
Ignorance of all things is an evil neither terrible nor excessive, nor yet the greatest of all; but great cleverness and much learning, if they be accompanied by a bad training, are a much greater misfortune.
No trace of slavery ought to mix with the studies of the freeborn man. No study, pursued under compulsion, remains rooted in the memory.
Walking is magic. Can't recommend it highly enough. I read that Plato and Aristotle did much of their brilliant thinking together while ambulating. The movement, the meditation, the health of the blood pumping, and the rhythm of footsteps... this is a primal way to connect with one's deeper self.
To prefer evil to good is not in human nature; and when a man is compelled to choose one of two evils, no one will choose the greater when he might have the less.
The first and greatest victory is to conquer yourself; to be conquered by yourself is of all things most shameful and vile.