as a consequence of the act A ; on the other hand, for whatever reason, I infer that this consequence is not immediate, but that outside my consciousness two facts B and C , which I have not witnessed, have happened, and in such a way that B is the effect of A , that C is the effect of B , and D of C .
But why? If I think I have reason to regard the four facts A, B, C, D, as bound to one another by a causal connection, why range them in the causal order A B C D, and at the same time in the chronologic order A B C D, rather than in any other order?
I clearly see that in the act A I have the feeling of having been active, while in undergoing the sensation D I have that of having been passive. This is why I regard A as the initial cause and D as the ultimate effect; this is why I put A at the beginning of the chain and D at the end; but why put B before C rather than C before B?
If this question is put, the reply ordinarily is: we know that it is B which is the cause of C because we always see B happen before C. These two phenomena, when witnessed, happen in a certain order; when analogous phenomena happen without witness, there is no reason to invert this order.
Doubtless, but take care; we never know directly the physical phenomena B and C. What we know are sensations B´ and C´ produced respectively by B and C. Our consciousness tells us immediately that B´ precedes C´ and we suppose that B and C succeed one another in the same order.
This rule appears in fact very natural, and yet we