I. Whoever directs his mind to the contemplation of the objects that surround him, the aggregate of which is called the universe, will soon perceive, that the parts of which it is composed undergo continually various modifications and successive changes, every one of them exercising some influence on the others, and receiving from them some alteration. This state of mutual dependence, in which the parts of the universe stand in relation to each other, leads us necessarily to conclude, that none of them has within itself the reason or cause of its existence, but that all of them together depend upon a cause which is out of themselves, and through which they began to exist; the universe, then, has had a cause, an Author.

II. This Author of the universe, if he had not in himself the reason of his existence, must also have it in others, and these again in others. Consequently, we must either suppose an endless progression of causes and effects, which is repugnant to reason, or arrive at last at a Being existing by and of himself, that is to say, one who owes not his existence to others, and has caused all other things to exist; and in that case, the reason of his existence must be part of his own essence and nature, and, consequently, inseparable from him and indestructible. The Author of the universe is then a Being necessary and eternal; and as to Him all things owe their existence, it follows that through Him they began to exist, and He created them from nought.

III. He, who could create all from nought, has a power without limits, and nothing is to Him impossible; He, who has given existence to all things, has also ordained the laws to which they are subject; He, who has ordained at His will the laws of nature, has also the power of changing or suspending them at His will; and lastly, He, who caused all things to exist, can alone keep them in existence, governing and directing them with ceaseless providence; and such continual action implies, of necessity, that He should know everything, that nothing should be hidden from Him, and that in Him error should be impossible. The Author of the universe is then omnipotent, free, all-provident, omniscient, and infallible.

IV. Again, whoever attentively contemplates the universe cannot help discovering, with admiration, in every part of it a stupendous art, a constant order, a systematic correspondence of means to ends, which demonstrate that all has been arranged on a predetermined plan and for a fixed purpose, to which all the particular dispositions developed in the course of the natural phenomena are exquisitely adapted. This order and this harmony which manifest themselves, also, in all the progressive courses of nature indicate a self-developing excellence, and a tendency to an ever-increasing perfectibility, such as can only emanate from a cause infinitely intelligent and good; and as such qualities cannot be attributed to a being corporeal, because limited and subject to changes, it follows that the Author of the universe is all-wise and good, pure and immutable.

V. Now, this Being, necessary and eternal, whom the contemplation of the universe alone reveals to us as the Author of everything, as omnipotent, free, all-provident, omniscient, infallible, pure, immutable, all-wise, and good, is He whom we call god.

VI. But our conviction of the existence of God need not be derived exclusively from the wonders of the universe; for every man can find in himself the evident proof of the existence of that supreme cause. In fact, man feels within himself that he thinks; and if he were even to doubt it, he could not deny that at least he doubts; and the doubt itself is already a thought. Admitting that he possesses the faculty of thinking, he must admit that there is within himself a substance, a being, a something which thinks. But this being, who is conscious of his own thoughts, is also conscious that he exists not by himself, that he has not existed from all eternity, that he is subject to changes, that even the simple ideas, which compose his thoughts, are not produced by himself, but acquired through his senses from external objects; and, in short, that he depends upon various causes placed without himself, and undergoes vicissitudes, which it is not in his power to remove. Therefore man has not within himself the reason of his own existence, but he must trace it to another, who is the Author of it. Now, this Author cannot have received His own existence from another, if He is to be considered the primary cause; otherwise we should fall into a succession of causes and effects to infinity. Then, the true Author of our existence is one who exists by Himself, and as such He is eternal, omnipotent, all-wise, etc., etc.; He is God.

VII. Another source, affording the proof of the existence of God, man finds in himself when his intellectual faculties have attained a certain degree of culture and maturity. He then knows himself to be a moral being; that is to say, a being who, placed between good and evil, can, of his own free will, adhere to the former and reject the latter, if he follows the dictates of his reason. Then the moral sense awakens in his mind the idea of a supreme blessing, of a progressive and infallible moral perfection, of a future final accord between virtue and felicity, and their necessary co-existence. Now, he cannot expect this supreme blessing from anything that surrounds him in nature, because he does not find in the latter the desired union of happiness with virtue, enjoyment with merit. He must, therefore, seek it in a Supreme Cause existing out of nature in a Cause which should contain in itself the type of the moral law, embrace the whole extent of that law with infinite intelligence, and act up to its dictates with a powerful will. This Supreme Cause is God.