The real explanation of these curious conjunctions of masculine and feminine names is, I think, not very hard to come by. Let us remember, in the first place, that they were found in the books of the priests, and that they belonged to forms of prayer--_comprecationes deorum immortalium_; in other words, they do not represent popular ideas of the deities, but ritualistic forms of invocation. As such they may indeed no doubt be regarded as expressing, or as growing out of, a popular way of thinking of the Power manifesting itself in the universe; but they are themselves none the less, like those strange lists of divine names called _Indigitamenta_, with which I shall deal directly, the creations of an active professional priesthood, working upon the principle that every deity must be addressed in precisely the correct way and no other, and accounting the name of the deity, as indicating his or her exact function, the most vitally important thing in the whole invocation. I have already pointed out how difficult the early Latin must have found it to discover how to address the _numina_ at work around him, and I shall return to the subject in another lecture; at present all I want to insist upon is that the priests of the City-state relieved him of this anxiety, and indeed must have carried the work so far as to develop a kind of science of divine nomenclature. Every one who has studied the history of religions knows well how strong the tendency is, when once invocation has become ritualised, for the names and titles of the objects of worship to abound and multiply. The Roman Church of to-day still shows this tendency in its elaborate invocation of the Virgin. With the old Romans the common method of elaboration lay in the invention of cult-titles, of which the different kinds have been distinguished and explained by Dr. J. B. Carter in his treatise "de Deorum Romanorum cognominibus."[310] Most of them are suggestive of function or character, as, _e.g._, Janus Patulcius Clusivius, or Jupiter Lucetius, Ops Opifera; sometimes they doubled the idea, as in Aius Locutius, or Anna Perenna, or Fors Fortuna; and in one or two cases they seem to have combined two deities together in rather puzzling conjunctions, which usually, however, admit of some possible explanation, as Janus Junonius, or Ops Consiva (_i.e._ Ops belonging to Consus).[311] In the Iguvian ritual, which is the highly-elaborated work of a priesthood as active as the Roman, we find combinations of not less than four names:[312] Cerfe Martie, Praestita Cerfia Cerfi Martii, Tursa Cerfia Cerfi Martii, which may perhaps be rendered "Spirit of Mars, protecting (female) spirit of the (male) spirit of Mars, fear-inspiring (female) spirit of the (male) spirit of Mars."