E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Frame of Mind.
Disposition. A printer’s frame is a stand on which the type is disposed; a founder’s frame is a mould into which molten metal is disposed or poured; a weaver’s frame is a loom where the silk or thread is disposed or stretched for quilting, etc.; a picture frame is an ornamental edging within which the picture is disposed; a mental frame, therefore, is the boundary within which the feelings of the mind are disposed. (Anglo-Saxon, fremm-an.)
