their Causes, and of all the Remedies wherewith Nature hath furnished us. Now having a designe to employ all my life in the enquiry of so necessary a Science; and having found a way, the following of which me thinks might infallibly lead us to it, unless we be hindred by the shortness of life, or by defect of experiments. I judg'd that there was no better Remedie against those two impediments, but faithfully to communicate to the publique, all that little I should discover, and to invite all good Wits to endevour to advance farther in contributing every one, according to his inclination and power, to those Experiments which are to be made, and communicating also to the publique all the things they should learn; so that the last, beginning where the precedent ended, and so joyning the lives and labors of many in one, we might all together advance further then any particular Man could do. I also observ'd touching Experiments, that they are still so much the more necessary, as we are more advanc'd in knowledg. For in the beginning it's better to use those only which of themselves are presented to our senses, and which we cannot be ignorant of, if we do but make the least reflections upon them, then to seek out the rarest and most studied ones. The reason whereof is, that those which are rarest, doe often deceive, when we seldome know the same of the most common ones, and that the circumstances on which they depend, are, as it were, always so particular, and so small, that it's very uneasie to finde them out. But the order I observed herein was this. First, I endevoured to finde in generall the Principles or first Causes of whatsoever is or may be in the world, without considering any thing for this end, but God alone who created it, or drawing them elsewhere, then from certain seeds of Truth which naturally are in our souls. After this, I examined what were the first and most ordinary Effects which might be deduced from these Causes: And me thinks that thereby I found out Heavens, Starrs, an Earth; and even on the Earth, Water, Air and Fire, Minerals, and some other such like things, which are the most common, and the most simple of all, and consequently the most easie to be understood. Afterwards, when I would descend to those which were more particular, there were so many severall ones presented themselves to me, that I did beleeve it impossible for a humane understanding to distinguish the forms and species of Bodies which are on the earth, from an infinite number of others which might be there, had it been the will of God so to place them: Nor by consequence to apply them to our use, unless we set the Effects before the Causes, and make use of divers particular experiments; In relation to which, revolving in my minde all those objects which ever were presented to my senses, I dare boldly say, I observed nothing which I could not fitly enough explain by the principles I had found. But I must also confesse that the power of