The question, "What are Space and Time?" with which Mr. Spencer opens his chapter on "Ultimate Scientific Ideas," introduces a subject common to all the Limitists, and which, therefore, should be considered in this part of our work. A remark made a few pages back, respecting an essay in the "North American Review" for October 1864, applies with equal force here in reference to another essay by the same writer, in the preceding July number of that periodical. At most, his view can only be unfolded. He has left nothing to be added. In discussing a subject so abstruse and difficult as this, it would seem, in the present stage of human thought at least, most satisfactory to set out from the Reason rather than the Sense, from the idea rather than the phenomenon; and so will we do. In general, then, it may be said that Space and Time are _a priori_ conditions of created being. The following extracts are in point. "Pure Space, therefore, as given in the primitive intuition, is pure form for any possible phenomenon. As unconjoined in the unity of any form, it is given in the primitive intuition, and is a cognition necessary and universal. Though now obtained from experience, and in chronological order subsequent to experience, yet is it no deduction from experience, nor at all given by experience; but it is wholly independent of all experience, prior to it, and without which it were impossible that any experience of outer object should be." "Pure Time, as given in the intuition, is immediately beheld to be conditional for all possible period, prior to any period being actually limited, and necessarily continuing, though all bounded period be taken away."--_Rational Psychology_, pp. 125, 128.