I have never liked the sentence about ignorance.
I like to use Websters 1828 edition for a real definition
Ignorance
IG'NORANCE, n. [L. ignorantia; ignoro,not to know; ignarus, ignorant; in and gnarus, knowing.]
1. Want, absence or destitution of knowledge;
the negative state of the mind which has not been instructed in arts, literature or science,
or has not been informed of facts. Ignorance may be general, or it may be limited to particular subjects. Ignorance of the law does not excuse a man for violating it.
Ignorance of facts if often venial.
Ignorance is preferable to error.
2. Ignorances, in the plural, is used sometimes for omissions or mistakes; but the use is uncommon and not to be encouraged.
Venial
VE'NIAL, a. [L. venia, pardon, leave to depart, from the root of venio, and signifying literally a going or passing.]
1. That may be forgiven; pardonable; as a venial fault or transgression. The reformed churches hold all sins to be venial, through the merits of the Redeemer; but the most trifling sins not to be venial, except through the righteousness and atonement of Christ.
2. In familiar language, excusable; that may be allowed or permitted to pass without censure; as a venial slip or fault.
3. Allowed.