The pro-slavery men formerly did apply it to abolition, and with excellent reason, if the use of it which I have criticized ever was correct; for it required great power of realizing in imagination the results of social change, and great power to follow and trust abstract reasoning, for any man bred under slavery to realize, in advance of experiment, the social and economic gain to be won--_most of all for the whites_--by emancipation. It now requires great power of “theoretical conception” for people who have no experience of the separation of church and state to realize its benefits and justice. Similar observations would hold true of all similar reforms. Free trade is a revolt, a conflict, a reform, a reaction and recuperation of the body politic, just as free conscience, free worship, free speech, free press, and free soil have been. It is in no sense a theory. 9. Protectionism is not a theory in the correct sense of the term, but it comes under some of the popular and incorrect uses of the word. It is purely dogmatic and _a priori_. It is desired to attain a certain object--wealth and national prosperity. Protective taxes are proposed as a means. It must be assumed that there is some connection between protective taxes and national prosperity, some relation of cause and effect, some sequence of expended energy and realized product, between protective taxes and national wealth. If then by theory we mean a speculative conjecture as to occult relations which have not been and cannot be traced in experience, protection would be a capital example. Another and parallel example was furnished by astrology, which assumed a causal relation between the movements of the planets and the fate of men, and built up quite an art of soothsaying on this assumption. Another example, paralleling protectionism in another feature, was alchemy, which, accepting as unquestionable the notion that we want to transmute lead into gold if we can, assumed that there was a philosopher’s stone, and set to work to find it through centuries of repetition of the method of “trial and failure.”