These considerations produced the book which is here offered to the publick, as better adapted to the great design of pleasing by instruction, than any which has hitherto been admitted into our seminaries of literature.  There are not indeed wanting in the world compendiums of science, but many were written at a time when philosophy was imperfect, as that of G. Valla; many contain only naked schemes, or synoptical tables, as that of Stierius; and others are too large and voluminous, as that of Alstedius; and, what is not to be considered as the least objection, they are generally in a language, which, to boys, is more difficult than the subject; and it is too hard a task to be condemned to learn a new science in an unknown tongue.  As in life, so in study, it is dangerous to do more things than one at a time; and the mind is not to be harassed with unnecessary obstructions, in a way, of which the natural and unavoidable asperity is such as too frequently produces despair.

If the language, however, had been the only objection to any of the volumes already extant, the schools might have been supplied at a small expense by a translation; but none could be found that was not so defective, redundant, or erroneous, as to be of more danger than use.  It was necessary then to examine, whether upon every single science there was not some treatise written for the use of scholars, which might be adapted to this design, so that a collection might be made from different authors, without the necessity of writing new systems.  This search was not wholly without success; for two authors were found, whose performances might be admitted with little alteration.  But so widely does this plan differ from all others, so much has the state of many kinds of learning been changed, or so unfortunately have they hitherto been cultivated, that none of the other subjects were explained in such a manner as was now required; and, therefore, neither care nor expense has been spared to obtain new lights, and procure to this book the merit of an original.

With what judgment the design has been formed, and with what skill it has been executed, the learned world is now to determine.  But before sentence shall pass, it is proper to explain more fully what has been intended, that censure may not be incurred by the omission of that which the original plan did not comprehend; to declare more particularly who they are to whose instructions these treatises pretend, that a charge of arrogance and presumption may be obviated; to lay down the reasons which directed the choice of the several subjects; and to explain more minutely the manner in which each particular part of these volumes is to be used.