This is because we have memory, which is itself a sensation; it is a sensation which prolongs itself; to remember is to feel that one has felt; it is to feel a former sensation which the brain is able to preserve. We think only by combining current sensations with other current sensations, or much more often indeed, thanks to memory, by combining current sensations with older ones, or former sensations with each other. This is but a fragile basis for knowledge and thought, for sensation is only a modification of ourselves caused by an external object, and consequently gives us nothing at all of the external object, and of itself the external world is eternally unknown to us; but we combine with each other the illusions that the external world deposits in us through the delusive or doubtful intermediary of our senses. When the sensation thus combined with other sensations has become thought, then ideas begin to exist. They are products of sensation detached from sensation. They are interassociated by laws that are obscure, yet which can be vaguely perceived. They awake, so to speak, and call to one another; every time an idea previously acquired reappears, it is followed by the thought which accompanied it when it was acquired. In a conversation a traitor is spoken of. Someone asks what was the value of a piece of silver in ancient times. This appears incoherent; really it is a natural and simple association of ideas in which there are few intermediate steps. The person who listened as the traitor was mentioned thought of Judas, who was the first traitor of whom he had heard, and of the thirty pieces of silver, the price of the betrayal by Judas. The association of ideas is more or less close, more or less loose; it is disconnected in dreams, irregular in musing, close directly it is dominated and in consequence directed by an end pursued, by a goal sought; for then there is a desire to attain which associates nothing of itself, but which, eliminating all ideas that are not pertinent to the end pursued, permits only the association of those which have relation to it. Seeing in the human soul only successive impulses arising from those first impulses which are the sensations, Hobbes does not believe we are free to do what we wish; we are carried away by the strongest impulse of our internal impulses, desire, fear, aversion, love, etc. Nevertheless we deliberate, we consider different courses to pursue and we decide on the one we desire to choose. No; we do not deliberate, we only imagine we deliberate. Deliberation is only a succession of different feelings, and to the one that gains the day we give the name of volition. "In the [so-called] deliberation, the final desire or the final fear is called will." Therefore liberty has no more existence among men than among animals; will and desire are only one and the same thing considered under different aspects.