FIRST of all, kind reader, I wish to explain why it was that I wrote this little work. On the one hand, I saw that our young men, not only laymen, but clerics also, had need of initiation in economic science, because it is interwoven with almost all the affairs of civil life; whilst, on the other, I found no course of instruction fitted to be a we guide for them. The earlier writers on Political Economy had their minds misled by the sensistic philosophy of their time; and philosophy, when bad, infects, being the root of them, all the other sciences. Those who came after followed their predecessors blindly, or, if they partly differed from them, wrote nevertheless under the influence of modem liberalism. Now, modem liberalism is like a blue-bottle fly. Wherever it settles, it leaves a germ of corruption and a bad smell. My intention, therefore, was to prepare something like a compendium of sound principles, that would suffice to put young men on the right road, along which they might proceed safely. In carrying out that idea I have, as you will see, availed myself of the theories taught by the best professors, but not without freely discussing their doctrines and refuting their errors. This book is not addressed to the learned. That would have required greater powers and more knowledge. It is meant for aspirants and novicos. Virginibus puerisque canto. I could have wished for more time to write it in; but my advanced age of nearly eighty years forbade me to expect that.