114 M. NOBILI ON COLOURS, AND ON A NEW CHROMATIC SCALE 
general law of the harmony of the eye will be this: That the corre- 
sponding colours in the Table hereafter mentioned will be in harmony 
with one another.” 
“In fact, if the organ of vision, after having been fixed on an orange 
colour, directs itself spontaneously, and uninfluenced by any external 
impulse, towards the indigo, or vice versd; or if in nature a violet- 
coloured hyacinth is placed beside a jonquil, and the optic axis is turned 
from the one flower upon the other, the centre of the retina passes over 
that succession of colours which is demanded by the nature of the or- 
gan and cannot be felt but with pleasure and satisfaction. These two 
colours harmonize, because the one leads to the other; and, for the con- 
trary reason, if the eye has to pass from one colour to another, not cor- 
responding with it in the table, it will necessarily have to make a dis- 
agreeable effort, because it will find itself in a position not in harmony 
with its former state. If the ocular harpsichord of Caslet were pos- 
sible, the modulation of the colours would be executed on it accord- 
ing to the principle just laid down*.” 
I will not deny that the aptitude of the retina to cause an imaginary 
to arise from a real colour is of some account in the effect produced by 
colour. I am even inclined to believe that colours attentively observed 
are, by this tendency of the organ, associated with a sentiment and 
endowed with an expression which they could not otherwise possess. 
This however would be a species of melody and not of harmony. 
Harmony is an instantaneous effect produced on the mind by several 
colours united altogether independent of the development of imaginary 
colours. Before this development can take place, the eye must be fixed 
for some time on a real colour; nor is this all, it is also necessary that 
the real colour should be seen in a bright light. Now, when I have 
one or two colours before my eyes, I can judge of their harmony with- 
out being obliged to look at them for a long time or requiring a very 
bright light. If I observe them for a single instant, my judgement is 
already pronounced, with the same promptitude with which the ear 
decides when it is affected by the harmony of sounds. Suppose for a 
moment that real sounds had their corresponding imaginary sounds, 
and the latter were determined when the ear had been for some time 
affected by a single quality of sounds suitably sustained. In the first 
place, these imaginary sounds could make no impression except in the 
particular case in which the notes are sustained for some time; but if 
we suppose that they accompanied the real sound necessarily and in 
every circumstance, they would not be in harmony with it; they would 
be perceived an instant after it, and would produce melody. 
When a particular colour is ill-assorted with another, the eye is of- 
fended, as the ear is hurt by adiscord. If. we pass from one of these 
« Venturi, Recherche Physique sur les Couleurs, for which the prize of the 
Italian Society was awarded. Modena, 1802. 
