Isaac Watts 
Logic or the Right Use of Reason in the Inquiry After Truth [PDF ebook] 
With a Variety of Rules to Guard Against Error in the Affairs of Religion and Human Life, as Well as in the Sciences

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. It is evident enough, from all these things, that our reason needs the assistance of art in our inquiries after trut/i or duty and, without some skill and diligence, forming our judgments aright, we shall be led into frequent mistakes, both in matters of science, and in matters of practice, and some of these mistakes may prove fatal too.