Erasmus Darwin (1731 – 1802)

First the new actions of the excited sense, Urged by appulses from without, commence; With these exertions pain, or pleasure, springs, And forms perceptions of external things. Thus, when illuminated by the solar beams, Yon waving woods, green lawns, and sparkling streams, In one bright point by rays converging lie Planed on the moving tablet of the eye; The mind obeys the silver goads of light, And irritation moves the nerves of sight.