Answer:
The ploughman and the splash of Icarus' fall.
Explanation:
Both poems - W. H. Auden's Musee des Beaux Arts and William's Landscape with the Fall of Icarus - describe a picture by Pieter Brueghel. In both poems, the speakers focus on how easily people are able to ignore the misfortune and suffering of the boy who has just fallen from the sky into the sea.
The element that is mentioned by both is authors is the ploughman who keeps on working, indifferent to the splash caused by Icarus' fall.
Auden's:
In Breughel's Icarus, for instance: how everything turns away
Quite leisurely from the disaster; the ploughman may
Have heard the splash, the forsaken cry,
But for him it was not an important failure; the sun shone
As it had to on the white legs disappearing into the green
William's:
According to Brueghel
when Icarus fell
it was spring
a farmer was ploughing
his field
the whole pageantry
of the year was
awake tingling
with itself
sweating in the sun
that melted
the wings' wax
unsignificantly
off the coast
there was
a splash quite unnoticed
this was
Icarus drowning