Potions of eysell 'gainst my strong infection;
No bitterness that I will bitter think,
Nor double penance to correct correction."
From Chaucer, Richardson's Dictionary supplies,
"She was like thing for hunger deed
That lad her life only by breed
Kneden with eisel strong and agre,
And thereto she was lean and megre."
Romaunt of the Rose.
and another passage thus: