We propose to call Altersign the Firstness of Secondness in the First Correlate. This sign mixes quality and existence without ever consubstantiating itself as full Secondness. Our inspiration was the term altersense, which Peirce uses as consciousness of alterity (CP 7.551). The Altersign is the Secondness in posse, a quality of “otherness” intrinsically present in all things before they manifest themselves to our senses as insistent reagents.