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Chapter I

    Throughout nature, wherever man strives to acquire knowledge he finds himself under the necessity of using special methods, 1st, to bring order among the infinitely numerous and varied objects which he has before him; 2nd, to distinguish, without danger of confusion, among this immense multitude of objects, either groups or those in which he is interested, or particular individuals among them; 3rd, to pass on to his fellows all what he has learnt, seen and thought on the subject.  Now the methods which he uses for this purpose are what I call the artificial devices in natural science, -- devices which we must beware of confusing with the laws and acts of nature herself.

    It is not merely necessary to distinguish in natural science what belongs to artifice and what to nature.  We have to distinguish as well two very different interests which incite us to the acquisition of knowledge.  

    The first is an interest which I call economic, because it derives its impetus from the economic and utilitarian needs of man in dealing with the productions of nature which he wants to turn to his own use.  From this point of view he is only interested in what he thinks may be useful to him.

    The other, very different from the first, is that philosophic interest through which we desire to know nature for her own sake, in order to grasp her procedure, her laws and operations, and to gain an idea of what she actually brings into existence.  This, in short, is the kind of knowledge which constitutes the true naturalist.  Those who approach the subject from this point of view are naturally few; they are interested impartially in all natural productions that they can observe.

    To begin with, economic and utilitarian requirements resulted in the successive invention of the various artificial devices employed
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in natural science.  When the interest of studying and knowing nature was felt, these artificial devices continued to be of assistance in the prosecution of that study.  These same artificial devices have therefore an indispensable utility, not only for helping us to a knowledge of special objects, but for facilitating study and the progress of natural science, and for enabling us to find our way about among the enormous quantity of different objects that we have to deal with.

    Now the philosophic interest embodied by the sciences in question, although less widespread than that which relates to our economic requirements, compels us to separate what belongs to artifice from what is the sphere of nature.  We have to confine within reasonable limits the consideration due to the first set of objects, and attach to the second all the importance that they deserve.

    The artificial devices in natural science are as follows:
    (1) Schematic classifications, both general and special.
    (2) Classes.
    (3) Orders.
    (4) Families.
    (5) Genera.
    (6) The nomenclature of various groups of individual objects.

    These six kinds of devices, commonly used in natural sciences, are purely artificial aids which we have to use in the arrangement and division of the various observed natural productions; to put us in the way of studying, comparing, recognising and citing them.  Nature has made nothing of the kind: and instead of deceiving ourselves into confusing our works with hers, we should recognise that classes, orders, families, genera and nomenclatures are weapons of our invention.  We could not do without them, but we must use them with discretion and determine them in accordance with settled principles, in order to avoid arbitrary changes which destroy all the advantages they bestow.

    It was no doubt indispensable to break up the productions of nature into groups, and to establish different kinds of divisions among them such as classes, orders, families and genera.  It was, moreover, necessary to fix what are called species, and to assign special names to these various sorts of objects.  This is required on account of the limitations of our faculties; some such means are necessary for helping us to fix the knowledge which we gain from that prodigious multitude of natural bodies which we can observe in their infinite diversity.

    But these groupings, of which several have been so happily drawn up by naturalists, are altogether artificial, as also are the divisions and sub-divisions which they represent.  Let me repeat that nothing
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of the kind is to be found in nature, notwithstanding the justification which they appear to derive from certain apparently isolated portions of the natural series with which we are acquainted.  We may, therefore, rest assured that among her productions nature has not really formed either classes, orders, families, genera or constant species, but only individuals who succeed one another and resemble those from which they sprung.  Now these individuals belong to infinitely diversified races, which blend together every variety of form and degree of organisation; and this is maintained by each without variation, so long as no cause of change acts upon them.