Condillac, animating his statue by degrees, and making the whole sum of human knowledge flow from one sensation, is like those priests who got inside the statue of the idol, and thence emitted their oracles. It is not the statue which receives animation, that speaks and thinks, it is Condillac from within it. Let us, however, grant to the sensist all he demands; let us allow him to regulate as he pleases the mutual dependence of sensations; for the instant we require him to make use only of pure sensations in his discussions, he will be utterly disconcerted, how much soever he may suppose them to be transformed. But we reserve these questions to the place in which we shall examine the nature and origin of ideas. 62. Why are we sure that the agreeable sensation which we experience in our sense of smell proceeds from an object called a _rose_? Because we recollect having experienced the same sensation on a thousand other occasions; because both sight and touch confirm the testimony of smell. But how do we know that these sensations are something beside the impressions received in our soul? Why may we not believe them to come from some cause or other, without relation to external causes? Is it because other men say the contrary? Are we certain that they exist? How do they know what they tell us? How do we know that we hear rightly? There is the same difficulty with the other senses as with that of hearing, and if we doubt the testimony of three senses, why shall we not doubt that of four? Reasoning is here of no avail; it would lead us to cavils which would require an impassible doubt, and would tear from us a security, of which, notwithstanding all our efforts, we cannot despoil ourselves. Moreover, if we appeal to the principles of reason, in order to prove the truth of sensation, we leave the territory of sensations, and do not place in them the primitive truth, origin of all other truths, nor accomplish what we undertook. 63. Hence it follows: First, that there is no one sensation which is the origin of the certainty of all others; this we have only indicated here, reserving the demonstration of it to our treatise on sensations. Secondly, although such a sensation were to exist, it could not serve as the basis of any thing in the intellectual order, for with sensation alone it is impossible even to think. Thirdly, that sensations, so far from being able to serve as the basis of transcendental science, cannot serve of themselves alone to establish any science; because necessary truths cannot flow from them, since they are contingent facts.(5) CHAPTER VI. TRANSCENDENTAL SCIENCE.--INSUFFICIENCY OF REAL TRUTHS.