Tertium Organum

our own
existence ­
that is, the existence of our inner life - and the existence of the external 
world 
in which we live. This, therefore, we must accept as 
data. 
But this is all we have the right to accept as 
data.
All the rest requires proof 
of its existence and definition on the basis of these two data we already 
possess. 
Space
with its extension; 
time,
with the idea of 
before, now
and 
after; 
quantity, mass, materiality; number, equality, inequality; 
identity and difference; cause and effect; ether, atoms, electrons, energy, life, 
death - all that is laid down as the basis of our usual knowledge, all these, are 
unknown quantities. 
The direct outcome of these two fundamental data - the existence in us of a 
psychological life, i.e. sensations, representations, concepts, thinking, feeling,
desires and so on, and the existence of the world outside us - is a division of 
everything we know into 
subjective 
and 
objective,
a division perfectly clear to 
our ordinary perception. 

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Everything we take to be the properties of the world, we call objective, and 
everything we take as properties of our inner life, we call subjective. 
The 'subjective world' we perceive 
directly;
it is in us; we are one with it. 
The 'objective world' we represent to ourselves as existing outside of us, 
apart from us as it were, and we take it to be exactly or approximately such as 
we see it. We and it are different things. It seems to us that if we close our 
eyes, the objective world will continue to exist, just as we saw it, and that, if 
our inner life, our subjective world, were to disappear, the objective world 
would go on existing as it existed when we, with our subjective world, were 
not there. 
Our relation to the objective world is most clearly denned by the fact that 
we perceive it as existing 
in time
and 
in space
and cannot perceive it or 
represent it to ourselves apart from these conditions. Usually, we say that the 
objective world consists of things and phenomena, i.e. of things and of 
changes in the state of things. A 
phenomenon
exists for us in time, a 
thing
exists in space. 
But such a division of the world into subjective and objective does not 
satisfy us.
By means of reasoning we can establish that, actually, we only know our 
own sensations, representations and concepts, and that we perceive the 
objective world by projecting outside of ourselves the presumed causes of our 
sensations. 
Further, we find that our cognition of both the subjective and the objective 
world may be 
true
or 
false,
correct or incorrect. 
The criterion for determining the correctness or incorrectness of our 
cognition of the subjective world is the form of relationship of one sensation 
to others, and the 
force
and character of the 
sensation itself. 
In other words, 
the correctness of one sensation is verified by comparing it with another of 
which we are more sure, or by the 
intensity and the taste of a given sensation. 
The criterion for determining the correctness or incorrectness of our 
cognition of the objective world is 
exactly the same.
It seems to us that we 
define things and phenomena of the objective world by means of comparing
them one with another; and we imagine that we discover the laws of their 
existence