In Works of Science and recondite Learning, the task you have undertaken will not be so difficult as you may imagine.  Tables of Contents and Indexes are blessed helps in the hands of a Reviewer; but, more than all, the Preface is the field from which his richest harvest is to be gathered.

In the Preface, the Author usually gives a summary of what has been written on the same subject before; he acknowledges the assistance he has received from different sources, and the reasons of his dissent from former Writers; he confesses that certain parts have been less attentively considered than others, and that information has come to his hands too late to be made use of; he points out many things in the composition of his Work which he thinks may provoke animadversion, and endeavours to defend or palliate his own practice.

Here then is a fund of wealth for the Reviewer, lying upon the very surface.  If he knows anything of his business, he will turn all these materials against the Author:  carefully suppressing the source of his information; and as if drawing from the stores of his own mind long ago laid up for this very purpose.  If the Author’s references are correct, a great point is gained; for by consulting a few passages of the original Works, it will be easy to discuss the subject with the air of having a previous knowledge of the whole.

Your chief vantage ground is, That you may fasten upon any position in the book you are reviewing, and treat it as principal and essential; when perhaps it is of little weight in the main argument:  but, by allotting a large share of your criticism to it, the reader will naturally be led to give it a proportionate importance, and to consider the merit of the Treatise at issue upon that single question.

If anybody complains that the greater and more valuable parts remain unnoticed; your answer is, That it is impossible to pay attention to all; and that your duty is rather to prevent the propagation of error, than to lavish praises upon that which, if really excellent, will work its way in the World without your help.

Indeed, if the plan of your Review admits of selection, you had better not meddle with Works of deep research and original speculation; such as have already attracted much notice, and cannot be treated superficially without fear of being found out.  The time required for making yourself thoroughly master of the subject is so great, that you may depend upon it they will never pay for the reviewing.  They are generally the fruit of long study, and of talents concentrated in the steady pursuit of one object:  it is not likely therefore that you can throw much new light on a question of this nature, or even plausibly combat the Author’s propositions; in the course of a few hours, which is all you can well afford to devote to them.  And without accomplishing one or the other of these points; your Review will gain no celebrity, and of course no good will be done.