 The worst physical symptom of Fechner’s growing illness was near blindness. He had strained his eyes doing his experimental work. He had to look through colored glasses at the sun, so that images of bright objects would remain in his eyes. He also had to stare for long periods at very fine measurement scales, which taxed his vision. His sight received “its final blow” in 1840. His eyes became so sensitive to light that he could not open them. He had to live in a completely darkened room and to wear a blindfold. Because of the deterioration of his sight, he had to abandon reading and writing; and because he could not read or write, he could not work. His great enemy became boredom. All could have been bearable to him if he could only sleep; but his insomnia was relentless. 