Benedict de Spinoza, THE ETHICS
Page: 37

their existence and presence. Further (II. xviii.), we showed
that, if the human body has once been affected by two external
bodies simultaneously, the mind, when it afterwards imagines one
of the said external bodies, will straightway remember the
other--that is, it will regard both as present to itself, unless
there arise causes which exclude their existence and presence.
Further, no one doubts that we imagine time, from the fact that
we imagine bodies to be moved some more slowly than others, some
more quickly, some at equal speed. Thus, let us suppose that a
child yesterday saw Peter for the first time in the morning, Paul
at noon, and Simon in the evening; then, that today he again
sees Peter in the morning. It is evident, from II. Prop.
xviii., that, as soon as he sees the morning light, he will
imagine that the sun will traverse the same parts of the sky, as
it did when he saw it on the preceding day; in other words, he
will imagine a complete day, and, together with his imagination
of the morning, he will imagine Peter; with noon, he will
imagine Paul; and with evening, he will imagine Simon--that is,
he will imagine the existence of Paul and Simon in relation to a
future time; on the other hand, if he sees Simon in the evening,
he will refer Peter and Paul to a past time, by imagining them
simultaneously with the imagination of a past time. If it
should at any time happen, that on some other evening the child
should see James instead of Simon, he will, on the following
morning, associate with his imagination of evening sometimes
Simon, sometimes James, not both together: for the child is
supposed to have seen, at evening, one or other of them, not
both together. His imagination will therefore waver; and, with
the imagination of future evenings, he will associate first one,
then the other--that is, he will imagine them in the future,
neither of them as certain, but both as contingent. This
wavering of the imagination will be the same, if the imagination
be concerned with things which we thus contemplate, standing in
relation to time past or time present: consequently, we may