Schreber 'girl strapped to bed'

Straps to insure proper posture during sleep.
(drawings from Moritz Schreber's writings - Daniel Paul's father)
"To succumb permanently to the power of attraction of such nerves would endanger God Himself; therefore one has to attempt to get away again when the purpose was achieved; one only had to produce little noises by miracle (the so-called "interferences") through which the attention of the sleeping, perhaps just waking, human being was diverted, and this short period of diverted attention sufficed the rays in the case of the nerves not as highly excited as mine, to give up the nerve-contact and enable them to withdraw from the person. Not really serious danger could arise for God while it was easy for rays to withdraw, as from only moderately excited nerves. These circumstances were then taken as pertaining equally to me without making allowance that my relation to divine rays had long ago became indissoluble owing to the enormously increased power of my nerves.

Daniel Paul Schreber, Memoirs of my Nervous Illness