Das Lichtmikroskop öffnete das erste Tor zum Mikrokosmos. Das Elektronenmikroskop öffnete das zweite Tor zum Mikrokosmos. Was werden wir finden wenn wir das dritte Tor öffnen?
as quoted by Nan Yao, director of the Imaging and Analysis Center at the Princeton Materials Institute, in the Princeton Weekly Bulletin, February 26, 2001, Vol. 90, No. 18 http://www.princeton.edu/~iac/pwb2_26b.html.
“He who wants to do good knocks at the gate; he who loves finds the gate open.”
88
Stray Birds (1916)
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Rabindranath Tagore 178
Bengali polymath 1861–1941Related quotes

“He would rather burst a city gate than find it open to admit him.”
Non tam portas intrare patentis
quam fregisse juvat.
Book II, line 443 (tr. J. D. Duff).
Pharsalia

"Although innumerable beings have been led to Nirvana no being has been led to Nirvana", §5, p. 85
Knots (1970)

speaking about Winston Churchill at the Reichstag, 4 May 1941 http://humanitas-international.org/showcase/chronography/speeches/1941-05-04.html.
1940s

“Love is the master key that opens the gates of happiness.”

A Mortal Antipathy (1885) This statement is often misquoted as "Love is the master-key that opens the gates of happiness".

“One who seeks will find, and for [one who knocks] it will be opened”
94
Gnostic Gospels, Gospel of Thomas (c. 2nd century AD manuscript)