We ought to consider our senses as messengers, which bring to our mind new subjects of reflection; but they are in such a manner subordinate to the sublime part of ourselves, that they act only under direction; sometimes the ruling principle commands them to bring representations of the beauties of nature, to examine assiduously the registers of the human mind, to take the rule and the compass, and render an exact account of that which it desires to know with precision; sometimes they are taught to acquire more power, and when the soul wishes to communicate with men, when it wishes to address posterity, it orders them to perpetuate in indelible characters all that it has maturely combined, all that it has discovered, and all it hopes to add to the treasures of our knowledge. Is it not the master rather than the slave of our senses, or the blind play of their caprice? There is besides another observation, which seems to contrast with the absolute empire, that some are willing to grant to exterior objects over the powers of our soul; for it is in the silence of meditation that the action of our mind is not interrupted: we experience that we have the power of recalling past ideas, and that we can connect those ideas with the prospect of the future, and to various imaginary circumstances of which we compose this picture; our reflection is then the result, but not the work of those exterior objects we are acquainted with. These two words, work and result, which in some acceptations have a great resemblance, have here very different meanings; and it is only in confounding them, that the objection against the existence of our liberty is favoured. We cannot form any judgment, without previously discussing every argument proper to throw a light on the subject; and the result of such enquiries determines our will; but these enquiries are themselves the work of our mind. In short, all the degrees which lead to the end of our intellectual researches, are simple antecedents, and not absolute motives: there is, in the operations of our mind, as in every thing which is not immoveable, a train of causes and effects; but this train does not characterize necessity more than liberty.