Meditations by Marcus Aurelius Book 3 Page 6

then shalt thou cease also to be subject to either pains or pleasures; and to serve and tend this vile cottage; so much the viler, by how much that which ministers unto it doth excel; the one being a rational substance, and a spirit, the other nothing but earth and blood.

IV. Spend not the remnant of thy days in thoughts and fancies concerning other men, when it is not in relation to some common good, when by it thou art hindered from some other better work. That is, spend not thy time in thinking, what such a man doth, and to what end: what he saith, and what he thinks, and what he is about, and such other things or curiosities, which make a man to rove and wander from the care and observation of that part of himself, which is rational, and overruling.

See therefore in the whole series