Mr 1:10 And straightway coming up out of the water, he saw the heavens opened, and the Spirit like a dove descending upon him:

When the heavens are opened, what can be seen? The firmament divides the waters above and below. ^[1] Jesus as the firmament, as the solid thing between the waters of baptism and the waters of heaven, could see both sides.

There were two things between the waters: the firmament, and the Spirit. ^{[2] [3]}

When there are two things, they are two aspects of the same thing. The two things between the waters are seen here to be one. The Spirit descended and rested upon him. The Spirit and the firmament are joined.

1. ↑ Ge 1:6 ¶ And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.
2. ↑ Ge 1:6 ¶ And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters.
3. ↑ Ge 1:2 And the earth was without form, and void; and darkness [was] upon the face of the deep. And the Spirit of God moved upon the face of the waters.