I shall divide what I am about to say into two parts: first, that a man may from the very beginning of his life give himself up entirely to the contemplation of truth; secondly, that a man when he has already completed his term of service, has the best of rights, that of his shattered health, to do this, and that he may then apply his mind to other studies after the manner of the Vestal virgins, who allot different duties to different years, first learn how to perform the sacred rites, and when they have learned them teach others.