Thus, it cannot be too often repeated, all the ideas, all the notions, all the modes of existence, and all the thoughts of man, are acquired. His mind cannot act, cannot exercise itself, but upon that of which it has knowledge; it can understand either well or ill, only those things which it has previously felt. Such of his ideas that do not suppose some exterior material object for their model, or one to which he is able to relate them, which are therefore called _abstract ideas_, are only modes in which his interior organ considers its own peculiar modifications, of which it chooses some without respect to others. The words which he uses to designate these ideas, such as _bounty, beauty, order, intelligence, virtue_, &c. do not offer any one sense, if he does not relate them to, or if he does not explain them by, those objects which his senses have shewn him to be susceptible of those qualities, or of those modes of existence, of that manner of acting, which is known to him. What is it that points out to him the vague idea of _beauty_, if he does not attach it to some object that has struck his senses in a peculiar manner, to which, in consequence, he attributes this quality? What is it that represents the word _intelligence_, if he does not connect it with a certain mode of being and of acting? Does the word _order_ signify any thing, if he does not relate it to a series of actions, to a chain of motion, by which he is affected in a certain manner? Is not the word _virtue_ void of sense, if he does not apply it to those dispositions of his fellows which produce known effects, different from those which result from contrary inclinations? What do the words _pain_ and _pleasure_ offer to his mind in the moment when his organs neither suffer nor enjoy, if it be not the modes in which he has been affected, of which his brain conserves the remembrance, of those impressions, which experience has shewn him to be either useful or prejudicial? But when he bears the words spirituality, immateriality, incorporeality, &c. pronounced, neither his senses nor his memory afford him any assistance; they do not furnish him with any means by which he can form an idea of their qualities, or of the objects to which he ought to apply them; in that which is not matter he can only see vacuum and emptiness, which as long as he remains what he is, cannot, to his mind, be susceptible of any one quality.