We are told that the angel in the illustration is Michael.
One writer says that "temperance" refers to the act of tempering, or the making of a properly balanced mixture. One no longer goes to extremes, but has mastery of the pairs of opposites; he now chooses a path somewhere between two extremes. Tempering refers to the blending of opposites to achieve synthesis. Blending must occur in the correct proportions.
Figure out how to integrate the various forces in your life. Remember that there is a difference between mixing things together and blending them.
Another writer has said that one cup is pouring water into the other; and that cup is pouring fire back into the first one (in the Rider-Waite version).
In the Crowley deck, this card is "Alchemy."
In the B.O.T.A. (Builders of the Adytum) deck (see illustration supra), the letters
יהוה
can be seen above the medallion on the angel's chest.
יהוה
is the "Tetragrammaton" the Hebrew name of God found in the Old Testament (6,807 times). An English Bible will render it
The Lord
in small caps, instead of actually translating (or transliterating) it.  
יהוה
does not mean "Lord."