Meditations of Marcus Aurelius Book XI
These are the properties of the rational soul: it sees itself, analyses itself, and makes itself such as it chooses; the fruit which it bears itself enjoys -- for the fruits of plants and that in animals which corresponds to fruits others enjoy -- it obtains its own end, wherever the limit of life may be fixed. Not as in a dance and in a play and in such like things, where the whole action is incomplete, if anything cuts it short; but in every part and wherever it may be stopped, it makes what has been set before it full and complete, so that it can say, I have what is my own. And further it traverses the whole universe, and the surrounding vacuum, and surveys its form, and it extends itself into the infinity of time, and embraces and comprehends the periodical renovation of all things, and it comprehends that those who come after us will see nothing new, nor have those before us seen anything more, but in a manner he who is forty years old, if he has any understanding at all, has seen by virtue of the uniformity that prevails all things which have been and all that will be. This too is a property of the rational soul, love of one's neighbour, and truth and modesty, and to value nothing more more than itself, which is also the property of Law. Thus then right reason differs not at all from the reason of justice.