We owe our liberation to chemistry," he went on. "For all perception is but a change in the concentration of hydrogen ions on the surface of the brain cells. Seeing me, you actually experience a disturbance in the sodium-potassium equilibrium across your neuron membranes. So all we have to-do is sent a few well-chosen molecules down into those cortical mitochondria, activate the right neurohumoral-synaptic transmission effector sites, and your fondest dreams come true. But you know all this," he concluded, subdued.

The Futurological Congress: From the Memoirs of Ijon Tichy