Meditations 1.16

Whatsoever I am, is either flesh, or life, or that which we commonly call the mistress and overruling part of man; reason. Away with thy books, suffer not thy mind any more to be distracted, and carried to and fro; for it will not be; but as even now ready to die, think little of thy flesh: blood, bones, and a skin; a pretty piece of knit and twisted work, consisting of nerves, veins and arteries; think no more of it, than so. And as for thy life, consider what it is; a wind; not one constant wind neither, but every moment of an hour let out, and sucked in again. The third, is thy ruling part; and here consider; Thou art an old man; suffer not that excellent part to be brought in subjection, and to become slavish: suffer it not to be drawn up and down with unreasonable and unsociable lusts and motions, as it were with wires and nerves; suffer it not any more, either to repine at anything now present, or to fear and fly anything to come, which the destiny hath appointed thee.