ve nothing square in this tower, but also that they discover
there a round shape, incompatible with the square shape. One may therefore
say that the truth which is the square shape is not only above, but even
against, the witness of our feeble sight.' It must be admitted that this
observation is correct, and although it be true that the appearance of
roundness comes simply from the effacement of the angles, which distance
causes to disappear, it is true, notwithstanding, that the round and the
square are opposites. Therefore my answer to this objection is that the
representation of the senses, even when they do all that in them lies, is
often contrary to the truth; but it is not the same with the faculty of
reasoning, when it does its duty, since a strictly reasoned argument is
nothing but a linking together of truths. And as for the sense of sight in
particular, it is well to consider that there are yet other false
appearances which come not from the 'feebleness of our eyes' nor from the
loss of visibility brought about by distance, but from the very _nature of
vision_, however perfect it be. It is thus, for instance, that the circle
seen sideways is changed into that kind of oval which among geometricians
is known as an ellipse, and sometimes even into a parabola or a hyperbola,
or actually into a straight line, witness the ring of Saturn.

65. The _external_ senses, properly speaking, do not deceive us. It is our
inner sense which often makes us go too fast. That occurs also in brute
beasts, as when a dog barks at his reflexion in the mirror: for beasts have
_consecutions_ of perception which resemble reasoning, and which occur also
in the inner sense of men, when their actions have only an empirical
quality. But beasts do nothing which compels us to believe that they have
what deserves to be properly called a _reasoning_ sense, as I have shown
elsewhere. Now when the understanding uses and follows the false decision
of the inner sense (as when the famous Galileo thought that Saturn had[110]
two handles) it is deceived by the judgement it makes upon the effect of
appearances, and it infers from them more than they imply. For the
appearances of the senses do not promise us absolutely the truth of things,
any more than dreams do. It is we who deceive ourselves by the use we make
of them, that is, by our consecutions. Indeed we allow ourselves to be
deluded by probable arguments, and we are inclined to think that phenomena