“Persistence is the key to solving most mysteries.”

Introduction as translated in Readings in European History, Vol. I (1904) edited by James Harvey Robinson, p. 451
Variant translation:
Constant and frequent questioning is the first key to wisdom … For through doubting we are led to inquire, and by inquiry we perceive the truth.
Prologue as translated in A History of Education During the Middle Ages and the Transition to Modern Times (1918) by Frank Pierrepont Graves; 2005 edition, p. 53<!-- translation of Prima sapientiae clavis definitur, assidua scilicet seu frequens interrogatio … Dubitando enim ad inquisitionem venimus; inquirendo veritatem percipimus. -->
Sic et Non (1120)
Context: I have ventured to bring together various dicta of the holy fathers, as they came to mind, and to formulate certain questions which were suggested by the seeming contradictions in the statements. These questions ought to serve to excite tender readers to a zealous inquiry into truth and so sharpen their wits. The master key of knowledge is, indeed, a persistent and frequent questioning. Aristotle, the most clear-sighted of all the philosophers, was desirous above all things else to arouse this questioning spirit, for in his Categories he exhorts a student as follows: "It may well be difficult to reach a positive conclusion in these matters unless they be frequently discussed. It is by no means fruitless to be doubtful on particular points." By doubting we come to examine, and by examining we reach the truth.

Source: Brida

Source: Big Stone Gap

Attributed to Merton in a number of sources, the earliest located being Studia mystica, Volumes 5-6 (1982), p. 76 http://books.google.com/books?id=59EYAAAAIAAJ&q=%22problem+to+be+solved%22#search_anchor. This does not attribute a direct quote to Merton, but says "To use another of Merton's favorite distinctions, for Furlong Merton's life is seen principally as a problem to be solved, which it was, in the final analysis, successfully, rather than a mystery to be lived". The next-earliest source located is the 1998 book The Artist's Way at Work: Riding the Dragon by Mark Bryan and Julia Cameron, which attributes the exact quote to Merton on p. 152 http://books.google.com/books?id=CghAQDPahhcC&lpg=PP1&pg=PA152#v=onepage&q&f=false. In reality this seems to be a slightly altered version of the quote "The mystery of life is not a problem to be solved; it is a reality to be experienced" which appeared in the 1928 book The Conquest of Illusion by Jacobus Johannes Leeuw, p. 9 http://books.google.com/books?id=OFdVAAAAMAAJ&q=%22not+a+problem+to+be+solved%22#search_anchor.
Misattributed

Variants:
Science cannot solve the ultimate mystery of nature. And that is because, in the last analysis, we ourselves are a part of the mystery that we are trying to solve.
Science cannot solve the ultimate mystery of nature, for in the final analysis we ourselves are part of the mystery we are trying to solve.
Source: Where is Science Going? (1932)

Source: Dune

"Hong Kong's likely leader pledges to "solidify" its international role" in Yahoo https://news.yahoo.com/hong-kongs-leadership-candidate-pledges-041612006.html (29 April 2022)

As translated by Jerome Rothenberg
Venetian Epigrams (1790)