It's a condition in which people see white or black dots in parts or the whole of their visual fields.
In opera, the libretto is the words or lyrics, as distinct from the music.
Relief is a sculptural technique where the sculpted elements remain attached to a solid background of the same material. The term relief is from the Latin verb relevo, to raise. To create a sculpture in relief is to give the impression that the sculpted material has been raised above the background plane.
Definition. A ground or primer, is the background surface on which you paint. It is usually a coating such as a gesso primer, which physically separates your painting from the support. It is the foundation of a painting, applied onto the raw canvas, paper, or other support.
In traditional pure etching, a metal (usually copper, zinc or steel) plate is covered with a waxy ground which is resistant to acid. The artist then scratches off the ground with a pointed etching needle where he or she wants a line to appear in the finished piece, so exposing the bare metal.
