the Greeks call [Greek: pathê] we choose to name perturbations (or
disorders) rather than diseases; in explaining which, I shall follow,
first, that very old description of Pythagoras, and afterward that of
Plato; for they both divide the mind into two parts, and make one of
these partake of reason, and the other they represent without it. In
that which partakes of reason they place tranquillity, that is to say,
a placid and undisturbed constancy; to the other they assign the turbid
motions of anger and desire, which are contrary and opposite to reason.
Let this, then, be our principle, the spring of all our reasonings. But
notwithstanding, I shall use the partitions and definitions of the
Stoics in describing these perturbations; who seem to me to have shown
very great acuteness on this question.

VI. Zeno's definition, then, is this: "A perturbation" (which he calls
a [Greek: pathos]) "is a commotion of the mind repugnant to reason, and
against nature." Some of them define it even more briefly, saying that
a perturbation is a somewhat too vehement appetite; but by too vehement
they mean an appetite that recedes further from the constancy of
nature. But they would have the divisions of perturbations to arise
from two imagined goods, and from two imagined evils; and thus they
become four: from the good proceed lust and joy--joy having reference
to some present good, and lust to some future one. They suppose fear
and grief to proceed from evils: fear from something future, grief from
something present; for whatever things are dreaded as approaching
always occasion grief when present. But joy and lust depend on the
opinion of good; as lust, being inflamed and provoked, is carried on
eagerly towards what has the appearance of good; and joy is transported
and exults on obtaining what was desired: for we naturally pursue those
things that have the appearance of good, and avoid the contrary.
Wherefore, as soon as anything that has the appearance of good presents