undoubtedly, propose a still more embarrassing question, by asking, of what use have the categories 
been? 
It has already been shown what Molière thought of them. Here is the opinion of the celebrated 
author of the Logic of Port Royal: “The study of the categories cannot but be 
dangerous, as it accustoms men to be satisfied with words, and to believe they know everything, 
when they are only acquainted with arbitrary names.” 
To this extravagant criticism, if it had fallen under his eyes, Ampère would have replied: That a 
natural classification of the sciences would be the model on which the sections of an institute 
claiming to represent the universality of human knowledge, should be scrupulously formed: That a 
natural classification of the sciences would indicate the proper omissions in the subjects of a 
well-arranged methodical encyclopedia. That a natural classification would control a rational 
distribution of the books in large libraries, a matter of so much importance that Liebnitz devoted 
to it much thought and labor: That a natural classification of the sciences would create a desirable 
revolution in the art of teaching. 
All this is just and true. But, unfortunately, the principles which a priori seemed to 
lead to natural classifications, have assimilated, grouped, and united the most incongruous 
subjects. 
If you take the encyclopedical tree of Bacon and D’Alembert, which is founded on the hypothesis, 
against which no objections have ever been raised, that the human mind can be reduced to three 
faculties – memory, reason, and imagination, – you will be led in the large division of 
knowledge depending on memory to classify the history of minerals and vegetables with civil history; 
and in sciences belonging to the domain of reason metaphysics will be associated with astronomy, 
ethics, and chemistry. 
Follow Locke or rather Plato, and theology and optics will be found side by side. Divide, as the 
schools of Rome do now, all knowledge into three kingdoms, the sciences of authority, of 
reason, and of observation, and anomalies almost laughable will arise at every 
step. 
These serious defects are not found in the classifications of Ampère. All analogous subjects are 
classed together; all that differ are separated. The author does not create at the will of 
his imagination pretended fundamental faculties for the basis of a system without solidity. His two 
chief points, his two kingdoms, are the study of the world – cosmology; and the 
study of the mind – ontology. 
The cosmological sciences are divided, in their turn, into two sub-kingdoms, namely, the 
sciences which treat of inanimate objects; and those which consider only animate objects. The first 
sub-kingdom of the cosmological sciences is divided again into two branches – the mathematical and 
physical sciences. By always following out this division by twos, Ampère succeeded in forming a 
table in which the whole range of sciences and arts is found divided –