_In these Conversations I have represented a woman receiving information on things with which she was entirely unacquainted. I thought this fiction would enable me to give the subject more ornament, and would encourage the female sex in the pursuit of knowledge, by the example of a woman who though ignorant of the sciences, is capable of understanding all she is told, and arranging in her ideas the worlds and vortices. Why should any woman allow the superiority of this imaginary Marchioness, who only believes what she could not avoid understanding?_ _'Tis true, she gives some attention to the subject, but what sort of attention is requisite? Not such as will laboriously penetrate into an obscure thing, or a thing that is spoken of in an obscure manner; it is needful only to read with sufficient application to render the ideas familiar. Women may understand this system of philosophy by giving it as much attention as they would bestow on the Princess of Cleves, in order to understand the story and see all the beauties of the work. I do not deny that the ideas contained in this book are less familiar to the generality of females than those in the Princess of Cleves, but they are not more abstruse, and I am convinced that on a second perusal they would be perfectly understood._ _As I did not wish to establish an imaginary system that had no foundation, I have employed true philosophical arguments, and as many of them as were necessary to establish my opinions; but fortunately the ideas connected with natural philosophy are in themselves beautiful, and whilst they satisfy the understanding, give as much pleasure as if formed only to charm the imagination._ _To such parts of my subjects as did not possess these beauties I have given extraneous ornaments; Virgil has done this in his Georgics, where he renders a dry subject interesting by frequent and agreeable digressions: Ovid likewise in his Art of Love has pursued the same plan, although the matter of his poem was far more pleasing than any thing he could add to it: he seems to think it tiresome to speak constantly of one subject--even of love. I have more need of embellishments than he, yet I have used them sparingly. I have only given such as the freedom of conversation authorised; I have only placed them in parts that I thought required them; I have inserted most of them in the commencement of the work to accustom the mind by degrees to the objects I wish to present to its attention, in short, I have derived them from my subject, or formed them as much as possible to resemble my subject._