Does anyone know a book that motivates the beginning of functional analysis in a clear way?

By "clear," I mean that it shows why one would want to define Hilbert spaces and why the theorems are motivated. I know of Dieudonne's *History of Functional Analysis*, but I am looking for something that also explains the theory.

I mean that it shows why one would want to define Hilbert spaces and why the theorems are motivated.While you'll probably get plenty of excellent answers to the question as asked, just keep in mind that the actual answer is thatnobodyhad any desire to define Hilbert spaces or to prove theorems for hundreds of thousands of years while the opportunity has always been there. We have many explanations of why one would do this or thatafterit has been done but all our attempts to project this teleology into the future and to squeeze any predictive value from it fail miserably.. $\endgroup$ – fedja Dec 1 '17 at 22:40History of Banach Spaces and Linear Operators, Birkhäuser, 2007. If you know German, the textbook by Dirk Werner contains a wealth of historical information in the corresponding chapters' appendices. $\endgroup$ – Christian Clason Dec 2 '17 at 8:50