the privation or absence of knowledge. The causes of ignorance, according to Locke, are chiefly these three. 1. Want of ideas. 2. Want of a discoverable connexion between the ideas we have. 3. Want of tracing and examining our ideas. See METAPHYSICS.

in a more particular sense, is used to denote illiteracy. Previous to the taking of Rome by the Gauls, such gross ignorance prevailed among the Romans that few of the citizens could read or write, and the alphabet was almost unknown. During three ages there were no public schools, but the little learning their children had was taught them by their parents; and how little that was may be partly concluded from this circumstance, that a nail was annually driven into the wall of the temple of Jupiter Capitolinus, on the 15th of September, to affix the ignorance of the people in reckoning the years, because they were unacquainted with letters or figures. The driving of the nail was afterwards converted into a religious ceremony, and performed by the dictator, to avert public calamities.

or mistake, in Law, a defect of will, whereby a person is excused from the guilt of a crime, when, intending to do a lawful act, he does that which is unlawful. For here the deed and the will acting separately, there is not that conjunction between them which is necessary to form a criminal act. But this must be an ignorance or mistake of fact, and not an error in point of law. As if a man intending to kill a thief or house-breaker in his own house, by mistake kills one of his own family, this is no criminal action: but if a man thinks he has a right to kill a person excommunicated or outlawed wherever he meets him, and does so; this is wilful murder. For a mistake in point of law, which every person of discretion not only may, but is bound and presumed to know, is, in criminal cases, no sort of defence. Ignorantia juris quod quisque tenetur seire, neminem excusat, is as well the maxim of our own law as it was of the Roman.