The Commens Dictionary
Quote from ‘Letters to Lady Welby’
I define a Sign as anything which is so determined by something else, called its Object, and so determines an effect upon a person, which effect I call its Interpretant, that the latter is thereby mediately determined by the former. My insertion of “upon a person” is a sop to Cerberus, because I despair of making my own broader conception understood.
In a variant of this passage, the "sop to Cerberus" refers to "mind" rather than "person"