as it moves in fact, by whatever hidden mechanism; as a locomotive engine could not move without steam, but still, under whatever number of forces, it certainly does start from Birmingham and does arrive in London. 4. And so again, as regards the first principles expressed in such propositions as “There is a right and a wrong,” “a true and a false,” “a just and an unjust,” “a beautiful and a deformed;” they are abstractions to which we give a notional assent in consequence of our particular experiences