Full Idea
The soul is not a mere rasa tabula, a naked and passive thing, with no innate furniture of its own, nor any thing in it, but what was impressed upon it without; for then there could not possibly be any such thing as moral good and evil, just and unjust.
Clarification
A 'rasa tabula' is a blank page
Gist of Idea
If the soul were a tabula rasa, with no innate ideas, there could be no moral goodness or justice
Source
Ralph Cudworth (On Eternal and Immutable Morality [1688], Bk IV Ch 6.4)
Book Reference
'British Moralists 1650-1800 Vol. 1', ed/tr. Raphael,D.D. [Hackett 1991], p.118
A Reaction
He goes on to quote Hobbes saying there is no good in objects themselves. I don't see why we must have an innate moral capacity, provided that we have a capacity to make judgements.