I. Thesis: Self-determination must lie at the basis of all causality, otherwise causality cannot be at all. II. Antithesis: If there is self-determination, “the unity of experience (which leads us to look for a cause) is destroyed, and hence no such case could arise in experience.” In comparing the two proofs it is at once seen that they are of different degrees of universality. The argument of the Thesis is based upon the nature of the thing itself, i. e. a pure thought; while that of the Antithesis loses sight of the idea of “_efficient_” cause, and seeks mere continuity in the sequence of time, and thus exhibits itself as the second stage of thought, which leans on the staff of fancy, i. e. mere _representative_ thinking. This “unity of experience,” as Kant calls it, is the same thing, stated in other words, that Spencer refers to as the “positive result of our mental structure.” In one sense those are true antinomies—those of Kant, Hamilton, _et al._—viz. in this: that the “_representative_” stage of thinking finds itself unable to shake off the sensuous picture, and think “_sub quadam specie æternitatis_.” To the mind disciplined to the third stage of thought, these are no antinomies; Spinoza, Leibnitz, Plato and Aristotle are not confused by them. The Thesis, properly stated, is a true universal, and exhibits its own truth, as that upon which the law of causality rests; and hence the antithesis itself—less universal—resting upon the law of causality, is based upon the Thesis. Moreover, the Thesis does not deny an infinite succession in time and space, it only states that there must be an efficient cause—just what the law of causality states, but shows, in addition, that this efficient cause must be a “self-determined.” On page 282 we learn that, “The solar heat is the final source of the force manifested by society.” “It (the force of society) is based on animal and vegetable products, and these in turn are dependent on the light and heat of the sun.” As an episode in this somewhat abstract discussion, it may be diverting to notice the question of priority of discovery, touched upon in the following note (p. 454): “Until I recently consulted his ‘Outlines of Astronomy’ on another question, I was not aware that, so far back as 1833, Sir John Herschel had enunciated the doctrine that ‘the sun’s rays are the ultimate source of almost every motion which takes place on the surface of the earth.’ He expressly includes all geologic, meteorologic, and vital actions; as also those which we produce by the combustion of coal. The late George Stephenson appears to have been wrongly credited with this last idea.”