The mind of men being very narrow and so slow in making acquaintance with things and taking in new truths that no one man is capable in a much longer life than ours,to know all truths,it becomes our prudence in our search after knowledge to employ our thoughts about fundamental and material questions,carefully avoiding those that are trifling and not suffering cursed is to be diverted from our main even purpose by those that are merely incidental.
How much of many young men's time is thrown away in purely logical enquiries,I need not mention.This is no better than if a man who was to be a painter should spend all his time in examining the threads of the several cloths he is to paint upon and counting the hairs of each pencil and brush he intends to use in the laying on of his colors.
Clay,it is much worse than for a young painter to spend his apprenticeship in such useless niceties;for he,at the end of all his pains to no purpose,finds that it is not painting nor any help to it,and so is really to no purpose.Whereas men designed for scholars have often their heads so filled and wanned with disputes on logical questions,that they take those airy useless notions for real and substantial knowledge and think their understandings so well furnished with science that they need not look any further into the nature of things or descend to the mechanical drudgery of experiment and enquiry.This is so obvious a mismanagement of the understanding,and that in the professed way to knowledge,that it could not be passed by;to which might be joined abundance of questions and the way of handling of them in the schools.What faults in particular of this kind every man is or may be guilty of would be infinite to enumerate;it suffices to have shown that superficial and slight discoveries and observations that contain nothing of moment in themselves,nor serve as clues to lead us into further knowledge,should be lightly passed by and never thought worth our searching after.
There are fundamental truths that lie at the bottom,the basis upon which a great many others rest and in which they have their consistency.These are teeming truths,rich in store with which they furnish the mind,and,like the lights of heaven,are not only beautiful and entertaining in themselves,but give light and evidence to other things that without them could not be seen or known.Such is that admirable discovery of Mr.Newton,that all bodies gravitate to one another,which may be counted as the basis of natural philosophy;which of what use it is to the understanding of the great frame of our solar system he has to the astonishment of the learned world shown;and how much further it would guide us in other things,if rightly pursued,is not yet known.Our Saviour's great rule,that we should love our neighbor as ourselves,is such a fundamental truth for the regulating human society,that,I think,by that alone one might without difficulty determine all the cases and doubts in social morality.These and such as these are the truths we should endeavor to find out and store our minds with.
Which leads me to another thing in the conduct of the understanding that is no less necessary,viz.:
