VaYikra 11:32

Verse 32. And in their state of complete vastation, even the least accidental indulgence therein causes impurity, whether such indulgence affects the will or understanding as receptacles of good or truth inwardly or outwardly; and any such receptacle that can be applied to use, must be brought under the influence of the truth, and remain impure until a change of state, so that it may serve its appointed purpose.