ate Motions._

GENUS IV.

_Catenated with External Influences._

As the diseases, which obey solar or lunar periods, commence with torpor or
inactivity, such as the cold paroxysms of fevers, the torpor and consequent
pain of hemicrania, and the pains which precede the fits of epilepsy and
convulsion, it would seem, that these diseases are more generally owing to
the diminution than to the excess of solar or lunar gravitation; as the
diseases, which originate from the influence of the matter of heat, are
much more generally in this country produced by the defect than by the
excess of that fluid.

The periodic returns of so many diseases coincide with the diurnal,
monthly, and annual rounds of time; that any one, who would deny the
influence of the sun and moon on the periods of quotidian, tertian, and
quartan fevers, must deny their effect on the tides, and on the seasons. It
has generally been believed, that solar and lunar effect was exerted on the
blood; which was thus rendered more or less stimulant to the system, as
described in Sect. XXXII. 6. But as the fluid matter of gravitation
permeates and covers all things, like the fluid matter of heat; I am
induced to believe, that gravitation acts in its medium state rather as a
causa sine qua non of animal motion, like heat; which may disorder the
system chemically or mechanically, when it is diminished; but may
nevertheless stimulate it, when increased, into animal exertion.

Without heat and motion, which some philosophers still believe to be the
same thing, as they so perpetually appear together, the particles of matter
would attract and move towards each other, and the whole universe freeze or
coalesce into one solid mass. These therefore counteract the gravitation of
bodies to one center; and not only prevent the planets from falling into
the sun, but become either the efficient causes of vegetable and animal
life, or the causes without which life cannot exist; as by their means the
component particles of matter are enabled to slide over each other with all
the various degrees of fluidity and repulsion.

As the attraction of the moon countervails or diminishes the terrene
gravitation of bodies on the surface of the earth; a tide rises on that
side of the earth, which is turned towards the moon; and follows it, as the
earth revolves. Another tide is raised at the same time on the opposite
side of the revolving earth; which is owing to the greater centrifugal
mo