"Some philosophers, departing as little as may be from the popular judgment, suppose that, however much of the apparent external world may be resolved into affections of the subjective sentiency, there still remains an objective residue of such primary qualities as extension, figure, divisibility, mobility, etc., belonging to external matter itself, and by the direct and immediate cognizance of which the mind is brought face to face with external substance, and knows something of its real goings-on. Philosophers of this school are known generally as REALISTS. More numerous, however, are those who, not allowing an objective and independent reality even to the so-called primary qualities of matter, but believing them as well as colour, odour, or savour, to be only affections of the sentiency, deny that the mind is in any sense brought face to face with real external things such as they seem in the act of perception. To thinkers of this school there has been given the general name of IDEALISTS. This broad distinction of Philosophers cosmologically into REALISTS and IDEALISTS is so far convenient enough. Cosmologically, or in respect of this present Universe of ours, with its dualism of Mind and Matter, every man must declare himself either a REALIST or an IDEALIST, if he understands the meanings attached to these terms. The distinction has reference solely to his notion of the so-called external or material world in its relations to the perceiving mind. If he abides, though only in part, by the popular conception, and regards the material world as a substantial reality independent of the perceiving mind, and which the mind, according to its powers, presses against and directly apprehends in every act of perception, then he is a REALIST. If, on the other hand, he cannot see that there need be asserted any external material world with such characters as we attribute to it, but supposes that our unanimous agreement in the imagination of such an external world is merely a habit of our own sentiency, projecting its own ideas or affections outwards, and giving them a body, then he is an IDEALIST." Masson, "_Recent British Philosophy_," pp. 58-64. Again p. 69, seq., "There is the system of _Constructive Idealism_. It may be so called to distinguish it from the more developed and extreme Idealism presently to be spoken of. According to this system, we do not perceive the real external world immediately, but only mediately--that is, the objects which we take as the things actually perceived are not the real objects at all, but only vicarious assurances, representatives, or nuntii of real unknown objects. The hills, the rocks, the trees, the stars, all the choir of heaven and earth, are not, in any of their qualities, primary, secondary, or whatever we choose to call them, the actual existences out of us, but only the addresses of a 'something' to our physiology, or eductions by our physiology out of a