We may see Heaven and Earth, Heaven and Hell, Male and Female, Sun and Earth, Good and Evil or any number of contraries.
"Without Contraries is no Progression" (MHH). Life begins with these contraries, but ends with a Unity. ("Everything that lives is holy"; end of MHH).
Blake's culture and our culture as well are patriarchal and have been in the Western World for a great many centuries. But go back earlier, and you may find a matriarchal one. That was the contribution of Sukie Colegrave, a Chinese-British woman of the second half of the 20th Century. Her book was entitled Uniting Heaven and Earth. Anthropology suggests that matriarchal cultures generally precede patriarchal ones.
The Perennial Philosphy points to the Sun as God (or Zeus) and the Earth as materiality, and to an Earth Goddess (There's a tremendous variety of Greek ones).
Jesus pointed to our loving Father in Heaven beginning the Lord's Prayer, and prayed that His will might be done on Earth. Charles Williams, a sort of Blakean writer wrote He Came Down from Heaven. (An autodidact like Blake, Williams' writing shows an uncanny relationship to Blake; one might call him a 20th century Blake!)
Blake's life was a continuous endeavor to raise Heaven on Earth. His wife complained about it, although as a faithful wife she supported him whole heartedly. He was called by one writer a Stranger from Paradise.