In thinking on this subject, nature always appears to me in the same point of view as theatrical representations. In the situation you occupy at the opera you do not see the whole of its arrangements: the machinery and decorations are so disposed as to produce an agreeable effect at a distance, and at the same time the weights and wheels are hidden by which every motion is effected. You behold all that is passing, without concerning yourself about the causes; and so perhaps do all the other spectators, unless among the number some obscure student of mechanics is puzzling himself to account for an extraordinary motion which he cannot understand. You see the case of this mechanical genius resembles that of the philosopher studying the structure of the universe. What, however, augments the difficulty with respect to philosophers is, that nature so conceals from us the means by which her scenery is produced, that for a long time we were unable to discover the causes of her most simple movements. Figure yourself, as spectators of an opera, the Pythagorases, the Platos, the Aristotles; all these men whose names are so celebrated. Let us suppose them viewing the flight of Phæton, rising on the wind; ignorant at the same time of the construction of the theatre, and the cords by which the figure is put in motion. One to explain the phenomenon, says, _it is some hidden virtue in Phæton which causes him to rise_; another replies, _Phæton is composed of certain numbers which produce his elevation_. A third says, _Phæton has a love for the top of the stage; he is uneasy at any other part_. The fourth thinks, _it is not essential to the nature of Phæton to rise in the air, but he prefers flying up to leaving a vacuum at the top of the stage_. Such were the ridiculous notions of the ancient philosophers, which to my astonishment have not ruined the reputation of antiquity. After all Descartes and some other moderns appear: they tell you that _Phæton rises in consequence of being drawn by cords, fastened to a descending weight, which is heavier than himself_. It is no longer believed that a body can have motion, unless acted upon by another body; that it can rise and descend without a counterbalancing weight; thus, whoever examines the mechanism of nature is only going behind the scenes of a theatre. If that be the case, answered the Marchioness, philosophy is a very mechanical affair! So much so, I replied, that I am afraid it will fall into disrepute. In short, the universe is but a watch on a larger scale; all its motions depending on determined laws and the mutual relation of its parts. Confess the truth, have you not hitherto entertained a more exalted idea of the works of nature? Have you not considered them with more veneration than they deserve? I have known some people esteem them less as their knowledge encreased. For my part, said she, I contemplate the universe with more awful delight now I