Descartes knew that, in order to understand the nature of things, they must be considered in their origin and birth; that we must always begin with the simplest and go first to their principle; that it is unnecessary to go to the trouble of discovering whether God formed His works gradually in the simplest ways or produced them all at once, but that in whatever way God had formed them, in order to understand them fully we must first consider them in their principles and take care only in the sequel that what has been thought agrees with what God has done.