The writer of the pamphlet before us is one of the few men who not only think for themselves, nut whose thoughts deserve attention. His essay on "The Law of the Territories" was distinguished not more by its sound reasoning than by the candor of its statements and the calmness of its tone and temper. If his later essay, on "The Laws of Race, as connected with Slavery," be on the whole less satisfactory, this is to be attributed, not to any want in it of the same qualities of thought and style as were displayed in his earlier work, but to the greater complexify and difficulty of the subject itself. The question of Race, so far as it affects actual national conditions, is one of the deepest and most intricate which can be presented to the student of politics. It is impossible to investigate it without meeting with difficulties which in the present state of knowledge cannot be solved, or without opening paths of speculation which no human foresight can trace to their end. This is, indeed, no reason for not attempting its discussion; and Mr. Fisher, in treating it in its relation to Slavery, has done good work, and has brought forward important, though much neglected considerations. He endeavors to place the whole subject of the relations of the white and the black races in this country on philosophic grounds, and to deduce the principles which must govern them from the teachings of ethnological science, or, in other words, from natural laws which human device can neither abrogate nor alter. From these teachings he derives the three following conclusions. "The white race must of necessity, by reason of its superiority, govern the negro, wherever the two live together. "The two races can never amalgamate, and form a new species of man, but must remain forever distinct,--though mulattoes and other grades always exist, because constantly renewed. "Each race has a tendency to occupy exclusively that portion of the country suited to its nature." If true, these conclusions are of the utmost importance. They are higher laws, which "must rule our politics and our destiny, either by the Constitution or over it, either with the Union or without it; and no wit or force of man is strong enough to resist them." It is to the exposition of the results which follow from these conclusions, assuming them to be true, that the larger part of the present essay is devoted. That these propositions express, or at least point the way to essential truths, we are fully persuaded. But we are not ready to accept all the inferences which the author draws from them, or to admit that they afford sufficient basis for some of his minor assumptions.