And thus, the moralist has before him a most ample field for speculation ; and one, as I have said, quite distinct from the field of speculation of the mathematician, and the physicist, and the naturalist. He has a world within for his empire, which, all within him as it is, is not smaller than the world without, to the eye of reason. The microcosm, the little world of man, is really not less than the macrocosm, the great world of nature. The moralist said what every moral thinker will feel to be true, when he declared that, great as was the impression of sublimity when he turned his eyes to the starry concave without him, he saw a spectacle no less solemn and awful, when he looked at the sphere of consciousness within.
And beyond all doubt, these two worlds affect us in a different manner, and are to be studied according to different methods. The true method, in each course, must lead, as I conceive, to a system of Truths ; but the very nature of the Truth appears to differ in the one system and in the other.
William Whewell, Lectures on Systematic Morality, p. 48. The microcosm/macrocosm comparison is traditional and goes back to Pythagoras. The moralist mentioned at the end of the first paragraph is Kant, of course.