He is blind enough who cannot see through a sieve.
More Spanish Proverbs:
Every one wishes to bring water to his own mill, and leave his neighbour's dry.Spanish
He who is afraid of a thing gives it power over him.
Spanish
Pour not water on a drowned mouse.
Spanish
Wherries must not put out to sea.
Spanish
The horseshoe that clatters wants a nail.
Spanish
Lovers think that others have no eyes.
Spanish