‘Paradiso II’; Dante and Beatrice in the sphere of the moon, with Beatrice explaining the nature of the heavens; illustration by Sandro Botticelli, c. 1490

 
What can we gain by sailing to the moon if we are unable to cross the abyss that separates us from ourselves? This is the most important of all voyages of discovery, and without it, all the rest are not only useless, but disastrous.
— Thomas Merton