When I begin, theoretically and practically I can smear anything I want on the canvas. Then there’s a condition I have to react to, by changing it or destroying it.
– Gerhard Richter
The immune system has evolved the capacity to react specifically with a very large number of foreign molecules with which it had no previous contact while avoiding reactivity for autologous molecules, naturally antigenic in other species or in other individuals of the same species.
– Baruj Benacerraf