In the second volume of the "Handbuch der physiologischen Optik", published in 1860, Helmholtz sets out a three-receptor theory of color vision using coterminal response curves, and shows that this theory can unify most phenomena of color mixing known at the time. Maxwell had publicized the same theory five years earlier, but Helmholtz barely acknowledges this fact in the "Handbuch". Some historians have argued that this is because Helmholtz independently discovered the theory around the same time as Maxwell. This paper argues that this hypothesis is implausible. By writing what he did in the "Handbuch", Helmholtz influenced the field's perception of its own history. As a result, Helmholtz has received more recognition for his contributions to the field of color mixing than was his due, and Maxwell less.