Truth is within ourselves; it takes no rise
From outward things, what'ere you may believe.
There is an inmost centre in us all,
Where truth abides in fulness; and around,
Wall upon wall, the gross flesh hems it in,
This perfect, clear perception -- which is truth ...
and to KNOW,
Rather consists in opening out a way
Whence the imprisoned splendor may escape,
Than in effecting entry for a light
Supposed to be without.

~ from "Paracelsus" by Robert Browning with thanks to John Bryan