The Idea that there is a Necessary Connection between Cause & Effect

If this is a meaningful and true idea, then (according to Hume) it must be derived from our sense impressions.
What, then, is the sense impression from which this idea is derived?
There is no sense impression of causal power or necessary connection of cause & effect, but we do experience the following. . . .
v(1) The spatial contiguity,
v(2) The temporal succession, and
v(3) The constant conjunction
........of "cause" & "effect."