— 634 —
This Certainty is as great as our Condition needs.
      §8. But yet, if after all this, any one will be so sceptical, as to
distrust his Senses, and to affirm, that all we see and hear, feel and
taste, think and do, during our whole Being, is but the series and
deluding appearances of a long Dream, whereof there is no reality;
and therefore will question the Existence of all Things, or our
Knowledge of any thing: I must desire him to consider, that if all be
a Dream, then he doth but dream, that he makes the Question; and
so it is not much matter, that a waking Man should answer him.
But yet, if he pleases, he may dream that I make him this answer,
That the certainty of Things existing in rerum Naturâ, when we have
the testimony of our Senses for it, is not only as great as our frame can
attain to, but as our Condition needs. For our Faculties being suited not
to the full extent of Being, nor to a perfect, clear, comprehensive
Knowledge of things free from all doubt and scruple; but to the
preservation of us, in whom they are; and accommodated to the use
of Life: they serve to our purpose well enough, if they will but give
us certain notice of those Things, which are convenient or incon-
venient to us. For he that sees a Candle burning, and hath experi-
mented the force of its Flame, by putting his Finger in it, will
little doubt, that this is something existing without him, which
does him harm, and puts him to great pain: which is assurance
enough, when no Man requires greater certainty to govern his
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Actions by, than what is as certain as his Actions themselves. And
if our Dreamer pleases to try, whether the glowing heat of a glass
Furnace, be barely a wandring Imagination in a drowsy Man’s
Fancy, by putting his Hand into it, he may perhaps be wakened into
a certainty greater than he could wish, that it is something more
than bare Imagination. So that this Evidence is as great, as we can
desire, being as certain to us, as our Pleasure or Pain; i.e. Happiness
or Misery; beyond which we have no concernment, either of Know-
ing or Being. Such an assurance of the Existence of Things without
us, is sufficient to direct us in the attaining the Good and avoiding
the Evil, which is caused by them, which is the important concern-
ment we have of being made acquainted with them.
Locke Hum IV, 11, §8, pp. 634-635