For categories $\mathcal{C}$ and $\mathcal{D}$, a pair of functors $\mathcal{C} \xrightarrow{\;R\;} \mathcal{D}$ and $\mathcal{C} \xleftarrow{\;L\;} \mathcal{D}\,$ are an adjoint pair if for any objects $X$ of $\mathcal{C}$ and $Y$ of $\mathcal{D}$ we have a bijection $\operatorname{Hom}_\mathcal{C}(LY,X) \simeq \operatorname{Hom}_\mathcal{D}(Y,RX).$ This adjoint relationship between $L$ and $R$ is often indicated by writing:
$$L \dashv R$$
Why do we use the symbol $\dashv\,$? Who originally used $\dashv$ in this context? I imagine that someone has asked this question before somewhere, right? But I couldn't find it here on MathSE or elsewhere.