Marginalia …

Toward the end of "Little Gidding," the last of  T. S. Eliot's Four Quartets, the following lines occur:

A condition of complete simplicity
(Costing not less than everything)

The line preceding these is this: "quick now, here, now, always," which is also the third from last line of "Burnt Norton," the first poem in the set. The phrase "quick now" is easy to overlook, almost as if it wanted to be like the now it refers to,  always on the move,  faster than everything.  Now is like the wind: You can feel it, but all that you can see of it is what it does — trees shaken in a gust, an old man pulling a thin coat tightly around himself to protect against it. Now is so quick, it is never quite ever. No sooner glimpsed than gone.
Whatever the connection between between "here, now, always" and the "condition of complete simplicity," it seems clear  it is the latter that costs "not less than everything."
That is the phrase that unnerves. Simplicity is not something that can be achieved. It can only be assented to by disposing of the baggage that gets in its way. That, I suspect, would be one's self. To attain complete simplicity, which I think is the same as " … to apprehend / The point of intersection of the timeless / With time" mentioned in "The Dry Salvages," the second of the Quartets, requires "a lifetime's death in love, / Ardour and selflessness and self-surrender."