When in the mind of man, Appetites, and Aversions, Hopes, and Feares, concerning one and the same thing, arise alternately; and divers good and evill consequences of the doing, or omitting the thing propounded, come successively into our thoughts; so that sometimes we have an Appetite to it; sometimes an Aversion from it; sometimes Hope to be able to do it; sometimes Despaire, or Feare to attempt it; the whole summe of Desires, Aversions, Hopes and Fears, continued till the thing be either done, or thought impossible, is that we call DELIBERATION.
Therefore of things past, there is no Deliberation; because manifestly impossible to be changed: nor of things known to be impossible, or thought so; because men know, or think such Deliberation vain. But of things impossible, which we think possible, we may Deliberate; not knowing it is in vain. And it is called Deliberation; because it is a putting an end to the Liberty we had of doing, or omitting, according to our own Appetite, or Aversion.
This alternate Succession of Appetites, Aversions, Hopes and Fears, is no lesse in other living Creatures then [sic] in Man: and therefore Beasts also Deliberate.
Every Deliberation is then sayd to End, when that whereof they Deliberate, is either done, or thought impossible; because till then wee retain the liberty of doing, or omitting, according to our Appetite, or Aversion.
In Deliberation, the last Appetite, or Aversion, immediately adhaering to the action, or to the omission thereof, is that wee call the WILL; the Act, (not the faculty,) of Willing. And Beasts that have Deliberation, must necessarily also have Will. The Definition of the Will, given commonly by the Schooles, that it is a Rationall Appetite, is not good. For if it were, then could there be no Voluntary Act against Reason. For a Voluntary Act is that, which proceedeth from the Will, and no other. But if in stead of a Rationall Appetite, we shall say an Appetite resulting from a precedent Deliberation, then the Definition is the same that I have given here. Will therefore is the last Appetite in Deliberating.
(Thomas Hobbes, Leviathan, rev. student ed., ed. Richard Tuck, Cambridge Texts in the History of Political Thought, ed. Raymond Geuss and Quentin Skinner [Cambridge: Cambridge University Press, 1996], chap. 6, pp. 44-5 [italics in original] [first published in 1651])