The connection of nightmare and horse seems, at first glance, to be present also etymologically—nightmare and mare. The Indo-Germanic root for märe is _mark_. Märe is the horse, English mare; Old High German _marah_ (male horse) and _meriha_ (female horse); Old Norse _merr_ (_mara_ = nightmare); Anglo-Saxon _myre_ (_maira_). The French “cauchmar” comes from _calcare_ = to tread, to step (of iterative meaning, therefore, “to tread” or press down). It was also said of the cock who stepped upon the hen. This movement is also typical for the nightmare; therefore, it is said of King Vanlandi, “Mara trad han,” the Mara trod on him in sleep even to death.[520] A synonym for nightmare is the “troll” or “treter”[521] (treader). This movement (_calcare_) is proven again by the experience of Freud and myself with children, where a special infantile sexual significance is attached to stepping or kicking. The common Aryan root _mar_ means “to die”; therefore, _mara_ the “dead” or “death.” From this results _mors_, μόρος = fate (also μοῖρα[522]). As is well known, the Nornes sitting under the “world-ash” personify fate like Clotho, Lachesis and Atropos. With the Celts the conception of the Fates probably passes into that of _matres_ and _matronæ_, which had a divine significance among the Germans. A well-known passage in Julius Cæsar (“De Bello Gallico,” i: 50) informs us of this meaning of the mother: “Ut matres familias eorum sortibus et vaticinationibus[523] declararent, utrum prœlium committi ex usu esset, nec ne.”[524] In Slav _mara_ means “witch”; poln. _mora_ = demon, nightmare; _mōr_ or _mōre_ (Swiss-German) means “sow,” also as an insult. The Bohemian _mura_ means “nightmare” and “evening moth, Sphinx.” This strange connection is explained through analysis where it often occurs that animals with movable shells (Venus shell) or wings are utilized for very transparent reasons as symbols of the female genitals.[525] The Sphingina are the twilight moths; they, like the nightmare, come in the darkness. Finally, it is to be observed that the sacred olive tree of Athens is called “μορία” (that was derived from μόρος). Halirrhotios wished to cut down the tree, but killed himself with the axe in the attempt.