BOOK I PART III
that means the idea, which I at present exam-
ine. For after a frequent repetition, I find, that
upon the appearance of one of the objects, the
mind is determined by custom to consider its
usual attendant, and to consider it in a stronger
light upon account of its relation to the first ob-
ject. It is this impression, then, or determina-
tion, which affords me the idea of necessity.
I doubt not but these consequences will at
first sight be received without difficulty, as be-
ing evident deductions from principles, which
we have already established, and which we
have often employed in our reasonings. This
evidence both in the first principles, and in the
deductions, may seduce us unwarily into the
conclusion, and make us imagine it contains
nothing extraordinary, nor worthy of our cu-
riosity. But though such an inadvertence may