When the aeronaut inflates his balloon with a gas specifically lighter than atmospheric air, or the ship-builder constructs vessels of wood or iron, so that when filled with air they shall be lighter than water, and float with their cargo on its surface, each is attempting to counteract the law of gravitation by the application of certain other related laws: but no one ever dreams of their _disobeying_ God in thus availing themselves of one physical agent to counterpoise another.

The "moral law," however, cannot be treated in the same way, and that simply because it is generically different.
It is true, that _indirectly_ the laws of Nature, when known, may and ought to regulate our practical conduct; not, however, by virtue of any obligation imposed _by them_ on our conscience, but solely by virtue of that law of _moral prudence_ which springs from conscience itself, and which teaches us that we _ought_ so to act with reference to outward objects as to secure, so far as we can, our own safety and happiness, and the welfare of our fellow-men.

But there can be no greater blunder than to confound _the laws of natural objects_ with _the law of human conduct_; and into this deplorable blunder Mr.Combe has allowed himself to fall.

Throughout the whole of his statements respecting the "natural laws," there are two things included under one name, which are perfectly distinct and separate from each other.

In the first place, there are the laws which belong to the constitution of natural objects, and which regulate their mutual action on one another: in the second place, there are, in the words of a late sagacious layman, "_rules_ which the intellect of man is able to deduce for the regulation of his own conduct, by means of his knowledge of those laws which govern the phenomena of Nature.