in the original Celtic version the “grail” (though not named this) is a severed head on a platter.
A severed head? Quite a grisly image if taken literally, but what about metaphorically?
The Celts saw the head as the seat of the soul, so from this perspective it could be read as the soul being seperated from the body, (or vice verse).
One could also interpret it as the head representing logical, rational “Head thoughts” being severed from the “heart feeling” of the body.
Either way this psychic seperation causes illness and the wasteland, both in terms of the land and the inner country of the individual’s mind.