A period may be defined as a portion of speech that has in itself a beginning and an end, being at the same time not too big to be taken in at a glance
AristotleIt is clear that there is some difference between ends: some ends are energeia [energy], while others are products which are additional to the energeia.
AristotleTragedy is an imitation not only of a complete action, but of events inspiring fear and pity. Such an effect is best produced when the events come on us by surprise; and the effect is heightened when, at the same time, they follow as cause and effect. The tragic wonder will then be great than if they happened of themselves or by accident; for even coincidences are most striking when they have an air of design.
Aristotle