The story's keynote aphorism, ("One sees clearly only with the heart. What is essential is invisible to the eye") was reworded and rewritten some 15 times before achieving its final phrasing. Saint-Exupéry also used a Dictaphone recorder to produce oral drafts for his typist. His initial 30,000-word working manuscript was distilled to less than half its original size through laborious editing sessions. Multiple versions of its many pages were created and its prose then polished over several drafts, with the author occasionally telephoning friends at 2:00 a.m. to solicit opinions on his newly written passages.