Feet together — the angels' single leg

Berakhot 10b: one who prays should place the feet together. The reason given is a piece of exegesis about anatomy — Ezekiel 1:7, describing the living creatures of the chariot vision: "and their feet were a straight foot", read as meaning the angels have no knee-joint and no gait, one undivided leg apiece.

So the instruction is: stand as something that cannot walk. Put your feet together and you have removed your own ability to leave, to shift weight, to drift. Which is a remarkably concrete way of saying what the prayer says — that for these few minutes you are somewhere you cannot casually walk out of. The angels in the vision are static because they are stationed. For the length of the Amidah, so are you. Layer: Talmudic and halakhic. The chariot-vision reading is the Talmud's own, not a later mystical overlay — the Merkavah material picks it up afterwards.