What is in the marrow is hard to take out of the bone.
More Irish Proverbs:
You must cut your coat according to your cloth.Irish
A disease known is half cured.
Irish
Nature breaks through the eyes of the cat.
Irish
Better fifty enemies outside the house than one within.
Irish
It's as hard to see a woman crying as it is to see a barefooted duck.
Irish
When the sky falls we'll all catch larks.
Irish