Leave and cleave,

It is written in the Torah, in the chapter Genesis (2:24) - but leaves the husband of his father and his mother, and he will cling to his wife, and they become one flesh.

And there's a lot of deep explanation of this Pasuk. We will focus on one of them.

In the language of Kabbalah, the Father and Mother is Sefirot HB. Their mated (spiritual connection) generates "filial Partzuf" or stage ZA ( "Small Face"). The emergence of a new stage in the spiritual, it is out of the "parent" state. Therefore it is said, "will leave his father and his mother."

In turn, ZA is the male principle (giving), therefore it is said "leave her husband" rather than "leave his wife."

And finally "mission" of ZA - the connection with the female (receiving), called Malchut and Nukva (female). How to say - "they will become one flesh."