Anton Torelló:
The double-bass as a solo instrument and the virtuoso playing it are often treated unjustly by the critic because the latter knows so little of the instrument, its nature and its possibilities. I would advise all critics whose knowledge of the doublebass is a purely theoretical one, to read what I consider the most technically valid and complete work ever written on the history and literature of the doublebass, Friedrich Warnecke's 'Der Kontrabass'. They would be then be better able to appreciate it and its difficulties, and not be so apt to dismiss it as an instrument any strong-muscled pianist or violinist can 'pick up' with 'no other help than a proper instruction book.'
(Frederick H. Martens: String Mastery, New York 1923, S. 290)