On the Vision of Colours. 29 
ten mention it, that several colours were injudici- 
ously named. The term pink, in reference to the 
flower of that name, seemed proper enough; but 
when the term red was substituted for pink, I 
thought it highly improper; it should have been 
blue, in my apprehension, as pink and blue appear 
to me very nearly allied; whilst pink and red have 
scarcely any relation. 
In the course of my application to the sciences, that 
~ of optics necessarily claimed attention; and I became 
pretty well acquainted with the theory of light and co- 
lours before I was apprized of any peculiarity in my 
vision. I had not, however, attended much to the 
practical discrimination of colours, owing, in some 
degree, to what I conceived to be a perplexity in 
their nomenclature. Since the year 1790, the occa- 
sional study of botany obliged me to attend more to 
colours than before. With respect to colours that 
were white, yellow, or green, I readily assented to the 
appropriate term. Blue, purple, pink, and crimson 
appeared rather less distinguishable; being, accord- 
ing to my idea, all referable to blue. I have often 
seriously asked a person whether a flower was blue 
or pink, but was generally considered to be in jest. 
Notwithstanding this, I was never convinced of a 
peculiarity in my vision, till I accidentally observed 
the colour of the flower of the Geranium zonale by 
candle-light, in the Autumn of 1792. The flower 
was pink, but it appeared to me almost an exact 
