4. All these systems of influence or non-influence may be listed under the general problem of the world's CAUSAL UNITY. If the minor causal influences among things should converge towards one common causal origin of them in the past, one great first cause for all that is, one might then speak of the absolute causal unity of the world. God's fiat on creation's day has figured in traditional philosophy as such an absolute cause and origin. Transcendental Idealism, translating 'creation' into 'thinking' (or 'willing to' think') calls the divine act 'eternal' rather than 'first'; but the union of the many here is absolute, just the same--the many would not BE, save for the One. Against this notion of the unity of origin of all there has always stood the pluralistic notion of an eternal self-existing many in the shape of atoms or even of spiritual units of some sort. The alternative has doubtless a pragmatic meaning, but perhaps, as far as these lectures go, we had better leave the question of unity of origin unsettled. 5. The most important sort of union that obtains among things, pragmatically speaking, is their GENERIC UNITY. Things exist in kinds, there are many specimens in each kind, and what the 'kind' implies for one specimen, it implies also for every other specimen of that kind. We can easily conceive that every fact in the world might be singular, that is, unlike any other fact and sole of its kind. In such a world of singulars our logic would be useless, for logic works by predicating of the single instance what is true of all its kind. With no two things alike in the world, we should be unable to reason from our past experiences to our future ones. The existence of so much generic unity in things is thus perhaps the most momentous pragmatic specification of what it may mean to say 'the world is One.' ABSOLUTE generic unity would obtain if there were one summum genus under which all things without exception could be eventually subsumed. 'Beings,' 'thinkables,' 'experiences,' would be candidates for this position. Whether the alternatives expressed by such words have any pragmatic significance or not, is another question which I prefer to leave unsettled just now.