I would here willingly have proceeded to exhibit the whole chain of truths which I deduced from these primary but as with a view to this it would have been necessary now to treat of many questions in dispute among the earned,with whom I do not wish to be embroiled,I believe that it will be better for me to refrain from this exposition,and only mention in general what these truths are,that the more judicious may be able to determine whether a more special account of them would conduce to the public advantage.I have ever remained firm in my original resolution to suppose no other principle than that of which I have recently availed myself in demonstrating the existence of God and of the soul,and to accept as true nothing that did not appear to me more clear and certain than the demonstrations of the geometers had formerly appeared;and yet I venture to state that not only have I found means to satisfy myself in a short time on all the principal difficulties which are usually treated of in philosophy,but I have also observed certain laws established in nature by God in such a manner,and of which he has impressed on our minds such notions,that after we have reflected sufficiently upon these,we cannot doubt that they are accurately observed in all that exists or takes place in the world and farther,by considering the concatenation of these laws,it appears to me that I have discovered many truths more useful and more important than all I had before learned,or even had expected to learn.
But because I have essayed to expound the chief of these discoveries in a treatise which certain considerations prevent me from publishing,I cannot make the results known more conveniently than by here giving a summary of the contents of this treatise.It was my design to comprise in it all that,before I set myself to write it,I thought I knew of the nature of material objects.But like the painters who,finding themselves unable to represent equally well on a plain surface all the different faces of a solid body,select one of the chief,on which alone they make the light fall,and throwing the rest into the shade,allow them to appear only in so far as they can be seen while looking at the principal one;so,fearing lest I should not be able to compense in my discourse all that was in my mind,I resolved to expound singly,though at considerable length,my opinions regarding light;then to take the opportunity of adding something on the sun and the fixed stars,since light almost wholly proceeds from them;on the heavens since they transmit it;on the planets,comets,and earth,since they reflect it;and particularly on all the bodies that are upon the earth,since they are either colored,or transparent,or luminous;and finally on man,since he is the spectator of these objects.
