There is no phaenomenon in nature, but what is compounded and modifyd by so many different circumstances, that in order to arrive at the decisive point, we must carefully separate whatever is superfluous, and enquire by new experiments, if every particular circumstance of the first experiment was essential to it.

These new experiments are liable to a discussion of the same kind; so that the utmost constancy is requird to make us persevere in our enquiry, and the utmost sagacity to choose the right way among so many that present themselves.

If this be the case even in natural philosophy, how much more in moral, where there is a much greater complication of circumstances, and where those views and sentiments, which are essential to any action of the mind, are so implicit and obscure, that they often escape our strictest attention, and are not only unaccountable in their causes, but even unknown in their existence?
I am much afraid lest the small success I meet with in my enquiries will make this observation bear the air of an apology rather than of boasting.
If any thing can give me security in this particular, it will be the enlarging of the sphere of my experiments as much as possible; for which reason it may be proper in this place to examine the reasoning faculty of brutes, as well as that of human creatures.
SECT.

XVI OF THE REASON OF ANIMALS Next to the ridicule of denying an evident truth, is that of taking much pains to defend it; and no truth appears to me more evident, than that beasts are endowd with thought and reason as well as men.

The arguments are in this case so obvious, that they never escape the most stupid and ignorant.
We are conscious, that we ourselves, in adapting means to ends, are guided by reason and design, and that it is not ignorantly nor casually we perform those actions, which tend to self-preservation, to the obtaining pleasure, and avoiding pain.