Maaseh Breishit and Maaseh Merkavah

Ma'aseh Breishit (Hebrew: מַעֲשֶׂה בְּרֵאשִׁית) and Ma'aseh Merkavah (מַעֲשֶׂה מֶרְכָּבָה), literally "work in the Beginning" and "work of the Chariot", are terms used in the Talmud for the esoteric doctrine of the universe, or for parts of it. Ma'aseh Bereshit, following the Genesis creation narrative, comprises the cosmogony of the Talmudic era; Ma'aseh Merkavah, based on the throne-chariot of Ezekiel 1 and other prophetic descriptions of divine manifestations like Isaiah 6, is concerned with the theosophic views of those times.

Source: Wikipedia — Maaseh Breishit and Maaseh Merkavah (CC BY-SA 4.0)