A great sin can enter by a small door.
More Welsh Proverbs:
If every fool wore a crown, we should all be kings.Welsh
He that would be a leader must be a bridge.
Welsh
A man without prudence is a ship without an anchor.
Welsh
Have a horse of your own and then you may borrow another's.
Welsh
Adversity brings knowledge, and knowledge wisdom.
Welsh
An Angel on the road, a Devil at the fireplace.
Welsh