Tertium Organum

x = y, y = x.
What 
do we actually know? The existence of consciousness in us and of the world outside 
us. Dualism or monism? Subjective and objective cognition. Where do the causes of 
sensations lie? Kant's system. Time and space. Mach's observation. What the physicist 
actually works with. 
Learn to discern the real from the false. 
The Voice of the Silence,
H.P.B. 
The most difficult thing is to know what we do know and what we do not 
know. 
Therefore, if we wish to know something, we must first of all establish 
what
we accept as data, and 
what
we consider requires definition and proof, 
that is, we must determine 
what 
we know already, and 
what 
we wish to know. 
In relation to our cognition of the world and of ourselves the conditions 
would be ideal if it were possible to accept 
nothing
as data and regard
everything
as requiring definition and proof. In other words, it would be best 
to assume that we know 
nothing, 
and take this as our starting point. 
Unfortunately, however, it is impossible to create such conditions. 
Something has to be laid down as a foundation, something must be accepted 
as known; otherwise we shall be constantly forced to define one unknown by 
means of another. 
On the other hand, we must be chary of accepting as known - as 
data ­
things that, actually, are completely unknown and merely presupposed -
the 
sought for. 
We have to be careful not to find ourselves in the position 
occupied by positivist philosophy in the nineteenth century. For a long time 
the basis of this philosophy was the recognition of the existence 
of matter 
(materialism); and later, of 
energy,
i.e. force or 
motion
(energetics), although
in actual fact matter and motion always remained the unknown quantities, x 
and 
y,
and were always denned by means of one another. 

---

It is perfectly clear that it is impossible to accept the thing 
sought for 
as the 
thing 
known;
and that we cannot define one unknown by means of another 
unknown. The result is nothing but the identity of two unknowns: 
x = y, y
= 
x. 
It is precisely this 
identity of unknown quantities 
which represents the 
ultimate conclusion arrived at by positivist philosophy.
Matter is that in which the changes called motion take place: and motion 
is those changes which take place in matter. 
What then do we know? 
We know that, from the very first step towards cognition, a man is struck 
by two obvious facts: 
The existence of the world in which he lives',
and 
the 
existence of consciousness in himself. 
Neither the one nor the other can he prove or disprove, but both of them are 
facts
for him, they are 
reality.
One may speculate about the mutual relationship of these two facts. One 
may attempt to reduce them to one, that is, to regard the psychological or 
inner world as a part, or a function, or a reflection of the outer world, or look 
upon the outer world as a part, or a function, or a reflection of the inner 
world. But this would mean a digression from facts, and all such concepts 
would not be self-evident for an ordinary, non-speculative view of the world 
and of oneself. On the contrary, the only 
fact
that remains 
self-evident
is the 
antithesis of our inner life and the external world. 
Later, we shall return to this fundamental proposition. But meanwhile we 
have no grounds for arguing against the obvious fact of