Premising that by intelligence I shall mean the character common to intelligent feelings, – such as those evoked by listening to a piece of concerted music, – intelligent actions, – though they rise no higher than a horse’s ordinary responses to even a driver’s touch, – and intelligent thought, I will suggest that a sign is anything which being intelligently determined by an Object in its turn intelligently determines an Interpretant, which thus becomes mediately determined by the Object.
http://www.commens.org/dictionary/entry/quote-pragmatism-69