In saying this we give the reasonable interpretation of 'association':--so far at least as association is supposed to be brought about by juxtaposition in time and space. Time and space, as Kant might say, give the schema--the sensible and visible reflex of the eternal and universal thought-relation: they are _a priori_ because they are in the physical world the _primitive_, the first phase and the lowest manifestation of that unity which as we know it in nature and mind always blends with sense, or displays itself in sensible forms. They are the first stamp of reality, of real Nature: with them we are in Nature, but it is an abstract shadowy nature. They mark the ascent (which only from the mere logician's standpoint shall we call the descent) of the abstract (pure) idea into the element of multiplicity, of opposition, of life and consciousness. In the psychical and intellectual world, again, as it rises to more perfect ideality (as it elicits more _meaning_ from crude _fact_) they lose their prominence; they sink into the powers of memory and imagination, which build up past and future into the unity of the ever present, until in their consummation they leave as their residual product the abstract element of pure thought: a thought which claims the attributes of universality and eternity, which claims, i. e., to merge or submerge in it all space and all time[6].
It is evident therefore that if an associationist theory, like that of Hume, proposes to explain the actual field of mental life by elements given in it, and by no other, it can only do so on certain assumptions, which may be summed up in the proposition that the mind--the real mental space and time even (and not its supposed 'image')--is at once subjective and objective, at once real and ideal, at once the field of operation, the force which directs operations, and the mind which is aware of itself and its acts. To say, as Hume appears to do, that an unintermittent long-established custom breeds _in us_ certain irresistible and essential habits of thought, can only refer to an unexplained and unnoticed duplication of the self. There is here, one self, which is only a bundle of fragments, of ideas intrinsically separate and only incidentally connected by outside pressure, which enter into ties, peradventure necessary or indissoluble, though not due to inner affinity. And there is another self which is a self-same unity, dividing and growing, or assimilating, acted upon but only because it solicits action, and in a way controlling the process going on within it. The difficulty for the investigator is to realise that these two selves are one. No amount of ingenuity will ever succeed in honestly showing unity to be the mere resultant--even should it be a fictitious or phenomenal unity--of the collisions and fortuitous attachments or detachments of different and independent reals. The reals which behave in such a way as to engender unities, to cause syntheses, are reals in a mind; and the mind must not merely, as it were, flow around them, but have them fluid members of itself. If they are reals, they are ideal-reals. You must begin with an ideal-unity which is also a real-unity, in which variety can play and by which it is controlled.