“These purely physical sensations possess, however, a moral signification, from which we are permitted to make valuable deductions.

“The first two have three distinct phases: 

“First degree, to see.

“Second degree, to look.

“Third degree, to observe.

“If we see a material, its color strikes us first and we say:  I have seen a red or yellow material, and this will be all.

“Applying ourselves more closely, we look at it and we define the peculiarities of the color.  We say:  it is bright red or dark red.

“In observing it we determine to what use it is destined.

“The eye is attracted by: 

“The color.

“The movement.

“The form.

“The number.

“The duration.

“We have just spoken of the color.

“The movement is personified by a series of gestures that people make or by a series of changes to which they subject things.

“The form is represented by the different outlines.

“The number by their quantity.

“The duration by their length; one will judge of the length of time it takes to walk a road by seeing the length of it.

“The act of listening is divided into three degrees.

“First degree, to hear.

“Second degree, to understand.

“Third degree, to reflect.

“If some one walking in the country hears a dog bark he perceives first a sound:  this is the act of hearing.

“He will distinguish that this sound is produced by the barking of a dog; this is the act of understanding.

“Reflection will lead him then to think that a house or a human being is near, for a dog goes rarely alone.

“If the things which are presented to our sight are complex, those which strike our ears are summed up in one word, sound, which has only one definition, the quality of the sound.

“Then follow the innumerable categories of sound that we distinguish only by means of comprehension and reflection, rendered so instinctive by habit that we may call them automatic, so far as those which relate to familiar sounds.

“The example which we have just given is a proof of this fact.

“Let us add that this habit develops each sensitive faculty to its highest degree.

“The inhabitants of the country can distinguish each species of bird by listening to his song; and the hermits, the wanderers, those who live with society on a perpetual war footing, perceive sounds which would not strike the ears of civilized people.

“Approximation is also one of the stones by whose aid we construct the edifice of common sense.

“Concerning the calculations of probabilities, the application of approximation will allow us to estimate the capacity or the probable duration of things.

“We can not say positively whether a man will live a definite number of years but we can affirm that he will never live until he is two hundred.