Meditations, Book IV, Sections 10 to 14

Meditations, Book IV, Sections 10 to 14, from Project Gutenberg. This is really good stuff:

X. These two rules, thou must have always in a readiness. First, do nothing at all, but what reason proceeding from that regal and supreme part, shall for the good and benefit of men, suggest unto thee. And secondly, if any man that is present shall be able to rectify thee or to turn thee from some erroneous persuasion, that thou be always ready to change thy mind, and this change to proceed, not from any respect of any pleasure or credit thereon depending, but always from some probable apparent ground of justice, or of some public good thereby to be furthered; or from some other such inducement. 

XI. Hast thou reason? I have. Why then makest thou not use of it? For if thy reason do her part, what more canst thou require? 

XII. As a part hitherto thou hast had a particular subsistence: and now shalt thou vanish away into the common substance of Him, who first begot thee, or rather thou shalt be resumed again into that original rational substance, out of which all others have issued, and are propagated. Many small pieces of frankincense are set upon the same altar, one drops first and is consumed, another after; and it comes all to one. 

XIII. Within ten days, if so happen, thou shalt be esteemed a god of them, who now if thou shalt return to the dogmata and to the honouring of reason, will esteem of thee no better than of a mere brute, and of an ape. 

XIV. Not as though thou hadst thousands of years to live. Death hangs over thee: whilst yet thou livest, whilst thou mayest, be good.

An alternative translation, from the Internet Classics Archive at MIT. Looking at the alternative translation side by side is really important. It clears up a lot of misunderstanding:

A man should always have these two rules in readiness; the one, to do only whatever the reason of the ruling and legislating faculty may suggest for the use of men; the other, to change thy opinion, if there is any one at hand who sets thee right and moves thee from any opinion. But this change of opinion must proceed only from a certain persuasion, as of what is just or of common advantage, and the like, not because it appears pleasant or brings reputation. 

Hast thou reason? I have.- Why then dost not thou use it? For if this does its own work, what else dost thou wish? 

Thou hast existed as a part. Thou shalt disappear in that which produced thee; but rather thou shalt be received back into its seminal principle by transmutation. Many grains of frankincense on the same altar: one falls before, another falls after; but it makes no difference. 

Within ten days thou wilt seem a god to those to whom thou art now a beast and an ape, if thou wilt return to thy principles and the worship of reason.  

Do not act as if thou wert going to live ten thousand years. Death hangs over thee. While thou livest, while it is in thy power, be good.