eferred to the
primary qualities of matter.

The several steps in the inductive investigation of the form of any nature
flow readily from the definition of the form itself. For that is always and
necessarily present when the nature is present, absent when it is absent,
decreases and increases according as the nature decreases and increases. It
is therefore requisite for the inquiry to have before us instances in which
the nature is present. The list of these is called the table of _Essence
and Presence_. Secondly, we must have instances in which the nature is
absent; only as such cases might be infinite, attention should be limited
to such of them as are most akin to the instances of presence.[84] The list
in this case is called table of _Absence in Proximity_. Thirdly, we must
have a number of instances in which the nature is present in different
degrees, either increasing or decreasing in the same subject, or variously
present in different subjects. This is the table of _Degrees_, or
_Comparison_. After the formation of these tables, we proceed to apply what
is perhaps the most valuable part of the Baconian method, and that in which
the author took most pride, the process of exclusion or rejection. This
elimination of the non-essential, grounded on the fundamental propositions
with regard to forms, is the most important of Bacon's contributions to the
logic of induction, and that in which, as he repeatedly says, his method
differs from all previous philosophies. It is evident that if the tables
were complete, and our notions of the respective phenomena clear, the
process of exclusion would be a merely mechanical _counting out_, and would
_infallibly_ lead to the detection of the cause or form. But it is just as
evident that these conditions can never be adequately fulfilled. Bacon saw
that his method was impracticable (though he seems to have thought the
difficulties not insuperable), and therefore set to work to devise new
helps, _adminicula_. These he enumerates in ii., _Aph._ 21:--_Prerogative
Instances, Supports of Induction, Rectification of Induction, Varying the
Investigation according to the Nature of the Subject, Prerogative Natures,
Limits of Investigation, Application to Practice, Preparations for
Investigation, the Ascending and Descending Scale of Axioms_. The remainder
of the _Organum_ is devoted to a consideration of the twenty-seven classes
of Prerogative Instances, and though it contains much that is bo