What message does Sam leave for Charley?

In The Third Level, Sam leaves a message for Charley through a letter, suggesting that Charley should “look for the third level” in the future and not give up on his belief. Sam hints that the third level may be a real place for those who are ready to escape the stress of modern life, and it is something Charley may find again if he continues to seek it. Sam’s message encourages Charley to hold on to his hope and faith in the possibility of finding a peaceful escape, even if it exists only in his imagination. This message underscores the theme of escape and yearning for a simpler, happier time in the face of contemporary pressures.

This question related to Chapter 1 English Vistas Class 12th NCERT.
From the Chapter 1. The Third Level.
Give answer according to your understanding.