the mind > mental capacity > knowledge > want of knowledge, ignorance > that which is unknown > be or become unknown [verb (intransitive)] (2)
Unfamiliar, unknown. Esp. in to grow out of (a person's) knowledge: to cease to be known, to become unknown or unfamiliar. Obsolete.
figurative. Comparative obscurity. Chiefly in phrases, to be in the shade, to be in retirement, to be little known; to cast, throw into the shade, put…