We do not pretend to _know_ all this, nor are we "as certain of it as that two and two make four." Such certainty, though desirable, is not to be had in complex physiological questions. But we set down these propositions as being, so far as we can make out, in the present state of science, the verdict of physiology in the matter. Future inquiry may reverse that verdict; but as the physiologic evidence now stands, there is a quite appreciable preponderance in favor of the practice of smoking. Such was our own conclusion long before we had ever known, or cared to know, the taste of a cigar or pipe; and such it remains after eight years' experience in smoking. We shall endeavor concisely to present the _rationale_ of the matter, dealing with some general doctrines likely to assist us both now and later, when we come to speak of alcohol. We do not suppose it necessary to overhaul and quote all that the illustrious Pereira, in his "Materia Medica,"[3] and Messrs. Johnston and Lewes, in their deservedly popular books, have said about the physiologic action of tobacco. Their works may easily be consulted by any one who is interested in the subject; and their verdict is in the main confined to the general proposition that, from the temperate use of tobacco in smoking, no deleterious results have ever been proved to follow. More modern and far more elaborate data for forming an opinion are to be found in the great treatise of Dr. Anstie, on "Stimulants and Narcotics," which we shall make the basis of the following argument.[4] [3] "I am not acquainted with any well-ascertained ill effects resulting from the habitual practice of smoking."--Pereira, _Materia Medica_, vol. ii., p. 1431. Tobacco "is used in immense quantities over the whole world as an article of luxury, without any bad effect having ever been clearly traced to it."--Christison on _Poisons_, p. 730. These two short sentences, from such consummate masters of their science as Christison and Pereira, should far more than outweigh all the volumes of ignorant denunciation which have been written by crammers, smatterers, and puritanical reformers, from King James down. [4] Only a basis, however. The argument as applied to tobacco, though a necessary corollary from Dr. Anstie's doctrines, is in no sense Dr. Anstie's argument. We are ourselves solely responsible for it.