In the Introduction to Ad.Scient.de Nat., c.2.  In exactly the same way, in the case of writing, various subsidiary forms and uses have been added whereby writing is made to be hidden, to be kept secret from the understanding of others, and to pass from hand to hand without the risk of discovery.  Thus is it brought about, especially when the processes referred to are not random processes, but take place with fixed method, that there comes into being a special art, whose function it is to provide us with a system of hidden writing.  Now it being the case that an art of this kind, as well in the ordinary private relations of life as in the course of our public duties, in war, and at other times of greatest stress, renders us no slight service, no one, I believe, can take it amiss, if I look upon this art as a genuine art, and proclaim it such, classing it among these arts which I have just enumerated; - with this concession, however, that if it dare not or ought not to advance side by side with these others, that is, with logic, grammar, rhetoric and poetry, it may at least, as the handmaid of grammar and rhetoric, follow close behind.  But, you will say, this institution of secret-making belongs not alone to writing, but to the voice as well, and in fact to other things also.  Quite true.  For, it was in this understanding of the matter that I said above, c.2, that besides Cryptography, there were Cryptology and Semaeology, and that I further assigned to these three divisions the single general term Cryptomenytics.  In fact, this last term, as including the other terms, should rightfully be used in the title of the present work, but I have preferred that the word Cryptography should receive this distinction, both because Cryptography is the division of the subject of which I have specially undertaken to treat, and because the practice of secret-making finds its broadest field in the intercourse of those who are separated in space from one another, between whom the means of communication is writing only, and not the voice.  Although, therefore, Cryptology logically comes first, still Cryptography is the broader term and takes precedence.  To Semaeology and Semaeography not much attention is given, since the treatment of thse subjects follows in close secondary relation to that of Cryptology and Cryptography.  The reason is, therefore, apparent, why passing by the general subject Cryptomenytic, I have taken only that special division which is the most important and have classed it along with the afore-mentioned subsidiary studies, logic, grammar, rhetoric and poetry.  I make no objections, however, should one wish, going beyond the limits of my present undertaking, to use either the word Cryptomenytics or the word Cryptology, provided he lose not sight of the fact that among the subsidiary studies this art which I am now about to expound has its place, and that by the side of these four this has taken its stand in line as the fifth.