“In the best books great men talk to us, give us their most precious thoughts, and pour their souls into ours. God be thanked for books.”

"The Sick Chamber," The New Monthly Magazine (August 1830), reprinted in Essays of William Hazlitt, selected and edited by Frank Carr (London, 1889)
Source: Essays of William Hazlitt: Selected and Edited, with Introduction and Notes, by Frank Carr

"Self-Culture", an address in Boston (September 1838) http://www.americanunitarian.org/selfculture.htm
Context: I have insisted on our own activity as essential to our progress; but we were not made to live or advance alone. Society is as needful to us as air or food. A child doomed to utter loneliness, growing up without sight or sound of human beings, would not put forth equal power with many brutes; and a man, never brought into contact with minds superior to his own, will probably run one and the same dull round of thought and action to the end of llfe.
It is chiefly through books that we enjoy intercourse with superior minds, and these invaluable means of communication are in the reach of all. In the best books great men talk to us, give us their most precious thoughts, and pour their souls into ours. God be thanked for books. They are the voices of the distant and the dead, and make us heirs of the spiritual life of past ages. Books are true levelers. They give to all, who will faithfully use them, the society, the spiritual presence, of the best and greatest of our race.

Source: The Pillars of the Earth

Continue therefore to read it and to regulate your life by its precepts.
Letter to Peter Augustus Jay, April 9, 1784.
1780s

Source: Moby-Dick or, The Whale

as reported in Josiah Hotchkiss Gilbert, Dictionary of Burning Words of Brilliant Writers (1895), p. 29.

Google search of the second sentence, in quotes, yields a trio of 2019 books alone, most (there and in following) attributing it to Kepler—e.g., see Prof Basden's 2019 work, [Foundations and Practice of Research: Adventures with Dooyeweerd's Philosophy, The Complex Activity of Research [§10—4.1 Less-Obvious Pistic Functioning in Research], Advances in Research Methods, Abingdon-on-Thames, UK, Taylor & Francis-Routledge, 1st, 9781138720688, https://www.amazon.com/Foundations-Practice-Research-Adventures-Dooyeweerds/dp/1138720682, February 25, 2020] (page 222).
While most citations of Kepler have been traced back to a translation of an original work, this quotation appears broadly without any such sourcing (e.g., Basden). Where it is sourced, the sources are either spurious (e.g., to the "New World Encyclopedia", a Paragon House/Unification Church product https://www.nytimes.com/1984/04/02/arts/unification-church-is-starting-a-publishing-house.html, wherein it is likewise unsourced), or to such sources as Henry Morris' 1988 creationist work, [Men of Science, Men of God: Great Scientists Who Believed the Bible, Green Forest, AR, Master Books, 21st reprint, 9780890510803, https://www.amazon.com/Men-Science-God-Henry-Morris/dp/0890510806, February 25, 2020] (page 21f).
Until a scholarly source is found that ties these statements to an original text from Kepler, they formally must be considered unattributed to Kepler.
Disputed quotes