The works of Francis Bacon, lord chancellor of England.

BooK II. NOVUM ORGANUM. 387
of the subject; 5. Of the prerogative natures with And, although all exclusion advances affirmation,
respect to investigation, or of what should be the yet this takes place more directly in the samle
first or last objects of our research; 6. Of the than in different subjects. But, if the form (as
limits of investigation, or a synopsis of all natures it is quite clear, from what has been advanced)
that exist in the universe; 7. Of the application exhibit itself in one subject, it leads to all. The
to practical purposes, or of what relates to man; more simple the migration is, the more valuable
8. Of the preparations for investigation; 9. And, is the instance. These migrating instances are,
lastly, of the ascending and descending scale of moreover, very useful in practice, for, since they
axioms. manifest the form, coupled with that which
22. Amongst the prerogative instances we will causes or destroys it, they point out the right pracfirst mention solitary instances. Solitary in- tice in some subjects, and thence there is an easy
stances are those which exhibit the required transition to those with which they are most
nature in subjects that have nothing in common allied. There is, however, a degree of danger
with any other subject than the nature in ques- which demands caution, namely, lest they should
tion; or which do not exhibit the required nature refer the form too much to its efficient cause, and
in subjects resembling others in every respect imbue, or, at least, tinge the understanding with
except that of the nature in question. For these a false notion of the form from the appearance of
instances manifestly remove prolixity, and acce- such cause; which is never more than a vehicle
lerate and confirm exclusion, so that a few of or conveyance of the form. This may easily be
themn are of as much avail as many. remedied by a proper application of exclusion.
For instance: let the inquiry be the nature of Let us then give an example of a migrating
colour: Prisms, crystalline gems, which yield instance. Let whiteness be the required nature;
colours not only internally but on the wall, dews, An instance which passes towards generation, is
&c., are solitary instances. For they have nothing glass in its entire, and in its powdered state; or
in common with the fixed colours in flowers and water in its natural state, and when agitated to
coloured gems, metals, woods, &c., except the froth. For glass, when entire, and water, in its
colour itself. Hence we easily deduce thatcolour natural state, are transparent and not white, but
is nothing but a modification of the image of the powdered glass and the froth of water are white,
incident and absorbed light, occasioned in the and not transparent. We must inquire, thereformer case by the different degrees of incidence, fore, what has happened to the glass or water in
in the latter by the various textures and forms of the course of this migration. For, it is manifest
bodies.-* These are solitary instances as regards that the form of whiteness is conveyed and introsi.militude. duced by the bruising of the glass and the agitaAgain, in the same inquiry, the distinct veins tion of the water. But nothing is found to have
of white and black in marble, and the variegated been introduced but a diminishing of the parts of
colours of flowers of the same species, are solitary the, glass and water, and the insertion of air. Yet
instances: for the black and white of marble, and this is no slight progress towards discovering the
the spots of white and purple in the flowers of the form of whiteness, namely, that two bodies, in
stock, agree in every respect but that of colour. themselves more or less transparent, (as air and
Thence we easily deduce that colour has not water, or air and glass,) when brought into conmuch to do with the intrinsic natures of any body, tact in minute portions, exhibit whiteness, from
but depends only on the coarser, and, as it were, the unequal refraction of the rays of light.
mechanical arrangement of the parts. These are But here we must also give an example of the
solitary instances as regards difference. We call danger and caution of which we spoke. For inthem both solitary or wild, to borrow a word from stance; it will readily occur to an understanding
the astronomers. perverted by efficients, that air is always necessary
23. In the second rank of prerogative instances for producing the form of whiteness, or that whitewe will consider M-Eigrating instances. In these, ness is only generated by transparent bodies,
the required nature passes towards generation, which suppositions are both fal~e, and proved to
having no previous existence, or towards corrup- be so by many exclusions. Nay, it will rather
tion, having first existed. In each of these divi- appear, (without any particular regard to air or
sions, therefore, the instances are always twofold, the like,) that all bodies which are even in such of
or rather, it is one instance, first in motion or on its their parts as affect the sight, exhibit transparenpassage, and then brought to the opposite conclu- cy, those which are uneven and of simple texture,
sion. These instances not only hasten and con- whiteness, those which are uneven and of comfirm exclusion, but also reduce affirmation, or the pound but regular texture, all the other colours exform itself, to a narrow compass. For, the form cept black, but those which are uneven and of a
must be something conferred by this migration, compound, irregular, and confused texture, exhibit
or, on the contrary, removed and destroyed by it. blackness. An example has been given, there.
* This very nearly approaches to Sir I. Newton's discovery of an instance m igrat ing towards generatio,f the decomposition of light by the prism. in the required nature of whiteness. An instance