“Measure what is measurable, and make measurable what is not so.”
Galileo Galilei (1564–1642) Italian mathematician, physicist, philosopher and astronomer
The quote is widely misattributed to Galilei, but is actually from two French scholars, Antoine-Augustin Cournot and Thomas-Henri Martin. See "Der messende Luchs: Zwei verbreitete Fehler in der Galilei-Literatur" by Andreas Kleinert in "NTM Zeitschrift für Geschichte der Wissenschaften, Technik und Medizin" May 2009, Volume 17, Issue 2, pp 199–206.
Attributed