The two terms of the sequence, with which we are thus furnished by an actual experience, is an act of the mind, or a volition, on the one hand, which we call an efficient cause; and a modification or change in inert, passive matter, on the other, which we call an effect. It is easy to see how we rise from this single experience to the universal maxim in question. We are so made and constituted, by the Author of our nature, that we cannot help believing in the uniformity of nature's laws, or sequences. Hence, whenever we see either term of the above sequence, we are necessarily compelled, by a fundamental law of belief, to infer the existence of the other. This fundamental law of belief, by which we repose the most implicit confidence in the uniformity of nature's sequences, has been recognized by many distinguished writers in modern times. It is well stated and illustrated by Dr. Chalmers. "The doctrine of innate ideas in the mind," says he, "is wholly different from the doctrine of innate tendencies in the mind--which tendencies may lie undeveloped till the excitement of some occasion have manifested or brought them forth. In a newly-formed mind, there is no idea of nature, or of a single object in nature; yet, no sooner is an object presented, or is an event observed to happen, than there is elicited the tendency of the mind to presume on the constancy of nature. At least as far back as our observation extends, the law of the mind is in full operation. Let an infant, for the first time in his life, strike on the table with a spoon; and, pleased with the noise, it will repeat that stroke with every appearance of a confident expectation that the noise will be repeated also. It counts on the invariableness wherewith the same consequent will follow the same antecedent. In the language of Dr. Thomas Brown, these two terms make up a sequence, and there seems to exist in the spirit of man not an underived, but an aboriginal faith in the uniformity of nature's sequences."--Nat. Theo. p. 121. Now, the two terms which we find connected in the case before us, is an act of the mind, and a change or modification of the body. The volition is the antecedent, and the motion of body is the consequent. And these two, by virtue of the law of belief above stated, we shall always expect to find conjoined. Wherever we discover a change or modification, for example, in the corporeal system of any other person, similar to that which results from our own volitions, we shall necessarily infer the existence of a prior act by which it was produced.