\section{Interpolation Functors}
\label{section:interpolation-functors}

\textit{"In the presence of so many different interpolation methods it seemed timely to study the general structure of all possible methods: to determine all of them and to analyze the properties which are common to all."} — \cite[Page 51]{aronszajn1964interpolation}. 

\textit{"This is how things appeared in 1965. Fifteen years later, it was found that the number
of interpolation methods at our disposal is not large."} — \cite[Page vi, Footnote 3]{brudnyi1991interpolation}. 

The above quotes are taken from \cite[Page 427]{PietschHistory}.