1and you had no other object viſible and ſtable, wherewith to make
compariſons to that, you could not perceive its motion?
compariſons to that, you could not perceive its motion?
SIMP. No, nor the ſtone it ſelf; for if I would ſee it, when
it is at the higheſt, I muſt raiſe up my head, and as it deſcendeth
I muſt hold it lower and lower, and in a word, muſt continually
move either that, or my eyes, following the motion of the ſaid
ſtone.
it is at the higheſt, I muſt raiſe up my head, and as it deſcendeth
I muſt hold it lower and lower, and in a word, muſt continually
move either that, or my eyes, following the motion of the ſaid
ſtone.
Whence the
tion of a cadent
dy is collected.
tion of a cadent
dy is collected.
SALV. You have now rightly anſwered: you know then that
the ſtone lyeth ſtill, when without moving your eye, you alwayes
ſee it before you; and you know that it moveth, when for the
keeping it in ſight, you muſt move the organ of ſight, the eye. So
then when ever without moving your eye, you continually
hold an object in the ſelf ſame aſpect, you do always judge it
immoveable.
the ſtone lyeth ſtill, when without moving your eye, you alwayes
ſee it before you; and you know that it moveth, when for the
keeping it in ſight, you muſt move the organ of ſight, the eye. So
then when ever without moving your eye, you continually
hold an object in the ſelf ſame aſpect, you do always judge it
immoveable.
The motion of
the eye argueth
the motion of the
object looked on.
the eye argueth
the motion of the
object looked on.
SIMP. I think it muſt needs be ſo.
SALV. Now fancy your ſelf to be in a ſhip, and to have fixed
your eye on the point of the Sail-yard: Do you think, that
cauſe the ſhip moveth very faſt, you muſt move your eye, to keep
your ſight alwayes upon the point of the Sail-yard, and to
low its motion?
your eye on the point of the Sail-yard: Do you think, that
cauſe the ſhip moveth very faſt, you muſt move your eye, to keep
your ſight alwayes upon the point of the Sail-yard, and to
low its motion?
SIMP. I am certain, that I ſhould need to make no change at
all; and that not only in the ſight; but if I had aimed a Musket
at it, I ſhould never have need, let the ſhip move how it will,
to ſtir it an hairs breadth to keep it full upon the ſame.
all; and that not only in the ſight; but if I had aimed a Musket
at it, I ſhould never have need, let the ſhip move how it will,
to ſtir it an hairs breadth to keep it full upon the ſame.
SALV. And this happens becauſe the motion, which the Ship
conferreth on the Sail-yard, it conferreth alſo upon you, and upon
your eye; ſo that you need not ſtir it a jot to behold the top of
the Sail-yard: and conſequently, it will ſeem to you
able. Now this Diſcourſe being applied to the revolution of the
Earth, and to the ſtone placed in the top of the Tower, in which
you cannot diſcern any motion, becauſe that you have that
tion which is neceſſary for the following of it, in common with it
from the Earth; ſo that you need not move your eye. When
gain there is conferred upon it the motion of deſcent, which is its
particular motion, and not yours, and that it is intermixed with the
circular, that part of the circular which is common to the ſtone,
and to the eye, continueth to be imperceptible, and the right
ly is perceived, for that to the perception of it, you muſt follow it
with your eye, looking lower and lower. I wiſh for the
ving of this Philoſopher, that I could adviſe him, that ſome time
or other going by water, he would carry along with him a Veſſel
of reaſonable depth full of water, and prepare a ball of wax, or
other matter that would deſcend very ſlowly to the bottome, ſo
that in a minute of an hour, it would ſcarce ſink a yard; and that
rowing the boat as faſt as could be, ſo that in a minute of an hour
conferreth on the Sail-yard, it conferreth alſo upon you, and upon
your eye; ſo that you need not ſtir it a jot to behold the top of
the Sail-yard: and conſequently, it will ſeem to you
able. Now this Diſcourſe being applied to the revolution of the
Earth, and to the ſtone placed in the top of the Tower, in which
you cannot diſcern any motion, becauſe that you have that
tion which is neceſſary for the following of it, in common with it
from the Earth; ſo that you need not move your eye. When
gain there is conferred upon it the motion of deſcent, which is its
particular motion, and not yours, and that it is intermixed with the
circular, that part of the circular which is common to the ſtone,
and to the eye, continueth to be imperceptible, and the right
ly is perceived, for that to the perception of it, you muſt follow it
with your eye, looking lower and lower. I wiſh for the
ving of this Philoſopher, that I could adviſe him, that ſome time
or other going by water, he would carry along with him a Veſſel
of reaſonable depth full of water, and prepare a ball of wax, or
other matter that would deſcend very ſlowly to the bottome, ſo
that in a minute of an hour, it would ſcarce ſink a yard; and that
rowing the boat as faſt as could be, ſo that in a minute of an hour