Every stone monument may equally be a monument to the dead; libations are made at stone cairns as well as at the grave. From this there arises the worship of the Chthonic Hermes, which was elaborated in the myth of the escort of souls, psychopompos. Hermes is invoked at libations to the dead, and graves are placed in his care.
— Walter Burkert
Hermes does not belong only to the crossroads, the market, the clever thief of cattle. He belongs equally to the stone, the cairn, the poured libation — and Burkert's observation presses us to feel why. The same marker that announces presence at the road announces the absence that is death. There is no distinction in the stone itself; the difference lives entirely in what the encounter with it does to the one who stops.
What this means for the soul is that Hermes as psychopomp is not a late theological addition but a structural necessity. A figure who crosses every boundary must eventually cross the one that cannot be uncrossed. He escorts because he is already the god of passage, and death is simply the passage that does not reverse. The libation poured at the cairn is the same gesture as the libation poured at the grave: an acknowledgment that something has moved beyond where you can follow, and a request — not a demand — that the crossing be attended.
Depth psychology inherited this when it named psyche as guide-worthy. The soul does not ascend; it is accompanied into what it cannot manage alone. The cairn is not a symbol to be decoded. It is the occasion of the gesture — and Hermes is real as long as the gesture is.
Walter Burkert·Greek Religion: Archaic and Classical·1977