THE OBJECTS OF SCIENCE 71

like one pea, but like two peas. But there is no real

deception in this. No one would affirm that the mere

touch of a surface can impart knowledge as to the bulk

and solidity of the object touched ; for this, we must also

have some experience of resistance. If, then, with the fore

and middle finger we simultaneously touch two opposite

surfaces and find we cannot bring our fingers together, the

feeling naturally arises (from long experienced associations

of sensations) that an obstacle in the form of a solid body

lies between them an obstacle situated between the adjacent

sides of those fingers. But if we cross our .fingers, then

the pea touches those sides of each finger which do not

ordinarily touch the same thing, but two different things,

and this makes the single pea naturally feel as if it were

two peas.

As everyone knows, various ingenious instruments have

been invented to produce optical delusions, but that in no way

makes the declaration of our perceptive faculty at all less

trustworthy. We are able, indeed, so to arrange things as to

invert or distort impressions ordinarily made, what wonder

then that our sense perceptions sometimes become inverted or

distorted likewise ? But it is generally the case that though

our sense-perception is changed, our intellectual perception

remains perfect all the time, and so enables us to be the better

amused by the sense-deception induced.

But, it may be urged, most people even now, and everyone

a few centuries ago, have been deceived by their senses with

respect to the motions of the sun and the earth, yet the fact

is, their senses did not deceive them. They only drew too

hasty an inference from what they saw, as a little reflexion

will, we think, make obvious. Our sight gives us no informa-

tion at all with respect to motion, save indirectly, /.^., as shown

by changes of relative position between objects. Thus, when

we are moving, we may, under some circumstances, be quite

like one pea, but like two peas. But there is no real

deception in this. No one would affirm that the mere

touch of a surface can impart knowledge as to the bulk

and solidity of the object touched ; for this, we must also

have some experience of resistance. If, then, with the fore

and middle finger we simultaneously touch two opposite

surfaces and find we cannot bring our fingers together, the

feeling naturally arises (from long experienced associations

of sensations) that an obstacle in the form of a solid body

lies between them an obstacle situated between the adjacent

sides of those fingers. But if we cross our .fingers, then

the pea touches those sides of each finger which do not

ordinarily touch the same thing, but two different things,

and this makes the single pea naturally feel as if it were

two peas.

As everyone knows, various ingenious instruments have

been invented to produce optical delusions, but that in no way

makes the declaration of our perceptive faculty at all less

trustworthy. We are able, indeed, so to arrange things as to

invert or distort impressions ordinarily made, what wonder

then that our sense perceptions sometimes become inverted or

distorted likewise ? But it is generally the case that though

our sense-perception is changed, our intellectual perception

remains perfect all the time, and so enables us to be the better

amused by the sense-deception induced.

But, it may be urged, most people even now, and everyone

a few centuries ago, have been deceived by their senses with

respect to the motions of the sun and the earth, yet the fact

is, their senses did not deceive them. They only drew too

hasty an inference from what they saw, as a little reflexion

will, we think, make obvious. Our sight gives us no informa-

tion at all with respect to motion, save indirectly, /.^., as shown

by changes of relative position between objects. Thus, when

we are moving, we may, under some circumstances, be quite