The English works of Thomas Hobbes of Malmesbury, Volume 07 (of 11)
Thomas Hobbes · en
Again, you would prove the angle of contact, if it be an angle, to be of
the same kind with a rectilineal angle, out of Euclid (III. 16); where
he says, _it is less than any acute angle_. And it follows well, that if
it be an angle, and less than any rectilineal angle, it is also of the
same kind with it. But, to my understanding, Euclid meant no more, but
that it was neither greater nor equal; which is as truly said of
heterogeneous, as of homogeneous quantities. If he meant otherwise, he
confirms the opinion of Clavius against you, or makes the quantity of an
angle to be a superficies, and indefinite. But I wonder how you dare
venture to determine whether two quantities be homogeneous or not,
without some definition of homogeneous (which is a hard word), that men
may understand what it meaneth.
In your eighth chapter you have nothing but Sir H. Savile’s authority,
who had not then resolved what to hold; but esteeming the angle of
contact, first, as others falsely did, by the superficies that lies
between the tangent and the arch, makes the angle of contact and a
rectilineal angle homogeneous; and afterwards, because no multiplication
of the angle of contact can make it equal to the least rectilineal
angle, with great ingenuity returneth to his former uncertainty.
In your ninth and tenth chapters you prove with much ado, that the
angles of like segments are equal; as if that might not have been taken
gratis by Peletarius, without demonstration. And yet your argument,
contained in the ninth chapter, is not a demonstration, but a
conjectural discourse upon the word _similitude_. And in the eleventh
chapter, wherein you answer to an objection, which might be made to your
argument in the precedent page, taken from the parallelism of two
concentric circles, though objection be of no moment, yet you have in
the same treatise of yours that which is much more foolish, which is
this, (p. 38, l. 12): “_Non enim magnitudo anguli_,” _&c._ _“_The_
magnitude of an angle is not to be estimated by that straddling of the
legs, which it hath without the point of concourse, but by that
straddling which it hath in the point of the concourse itself._” I pray
you tell me what straddling there is of two coincident points,
especially such points as you say are nothing? When did you ever see two
nothings straddle?