…which is the joining together of the Ruach – i.e. the interior… On the level of the Ruach the connection is a double one: the Ruach of the Male is in the Nukva and that of the Nukva is in the Male (see Pitchey Chochmah VaDaat ch. 95, Klalut HaIlan 6:6). This is because the purpose of the Coupling of Kisses is to arouse the power of the Supreme Unity so as to forge an actual connection. This is not so in the case of the Coupling of the Yesods, whose purpose is only to send influence. Before the influence flows, they must be attached to one another with proximity of the flesh. However influence is sent only from the Male to the Female (unlike in the Coupling of Kisses, where the giving is mutual and each becomes included in the other).