Another primary truth is personal identity.
This is the knowledge of ourselves; the identifying of ourselves with our self-existence. We know that we exist, and in that existence we recognize our personality.
Man is composed of matter and mind, by some mysterious combination united; and we may divide our identity into mental and bodily.
Mental identity is the continuance and oneness of the thinking and reasoning principle. It is not divisible in length, breadth and dimensions composed of particles etc. like matter, nor does it change or cease to exist. It remains as it was originally with all its eternal powers its eternal principles.
Bodily identity is the sameness of the bodily organization the man in figure, as we behold him with our natural eyes. The particles of matter of which the body is composed may change; but its shape and structure and its physical creation are the same.
Professor Upham, in his work on Intellectual Philosophy, in reference to this subject, uses the following language:
"It was a saying of Seneca, that no man bathes twice in the same river; and still we call it the same, although the water within its banks is constantly passing away, and in like manner, we identify the human body, although it constantly changes."
Personal identity, then, comprehends the man as we behold him, in his bodily and mental nature, mysteriously and wonderfully made!
The old soldier, who has fought the battles of his country in the days of the American Revolution, will recount his deeds of valor and his heroic sufferings to his youthful listeners, not doubting, that he is really the same old soldier, who was in his country's service some sixty years since.
The early settlers of our country, as they look abroad over the cultivated plain, never doubt, that they are really the same individuals, who some forty years felled the trees of the forest and turned the wilderness into a fruitful garden!
So is man constituted, that his own identity is one of the first primary truths.
We are so constituted that we believe, or rather there seems to be an authoritative principle within us of giving confidence or credence to certain propositions and truths, which are presented to our minds. Among the first things which the mind admits is that there is no beginning or change without a cause, that nothing could not create something. When any new principle is discovered, man immediately seeks out the cause, looks for some moving power, as though it could not be self-creative and self-acting.
In contemplating the material universe, in beholding the beautiful planetary system, the sun, the moon and the stars regulated and controlled by undeviating laws, who does not say, these are the results of some mighty creative intelligence! That the power of their existences and harmonious motions was originated beyond themselves. Thus it is that we attribute to every effect a cause to every result a motive power. Matter and mind have uniform, undeviating and fixed laws. And they are always subject to and controlled by them. We are not to suppose otherwise, unless we give up our belief that any object is governed or directed. Yet we are not to suppose that the same laws apply both to matter and mind. Each has its peculiar governing principle, and in as much as mind, in its nature, deviates from matter, so may its laws deviate.
We all believe that the earth will continue to revolve on its axis and perform its annual orbit around the sun, that summer and winter, seed-time and harvest will continue to succeed each other, "that the decaying plants of autumn will revive again in spring." This belief does not arise in the mind at once; but has its origin now in one instance and then in another, until it becomes universal.