Analysis:
This quatrain by Saadi Shirazi paints a vivid picture of a longing for solitude and intimacy with a beloved.

Escape from the World: The speaker invites their beloved to escape the bustling city and find solace in the tranquility of the desert. This suggests a desire to break free from societal constraints and expectations.
Intimate Connection: The repeated phrase "you and I" emphasizes the deep connection between the speaker and their beloved. The desert becomes a symbol of their private world, free from outside influences.
The Ideal Moment: The speaker posits that true happiness can only be achieved when they are completely alone with their beloved. This suggests a desire for an intimate and exclusive connection.

Themes:

Love and Intimacy: The central theme is the longing for deep and intimate connection with a beloved.
Escape: The speaker seeks to escape the demands of society and find solace in nature.
Solitude: The ideal of being alone with one's beloved is presented as a source of happiness.

Deeper Meaning:
This quatrain speaks to the universal human desire for connection and intimacy. The desert, often seen as a symbol of solitude and isolation, becomes a place of refuge and renewal in this context. The speaker is not seeking to escape the world entirely, but rather to find a place where they can connect with their beloved on a deeper level, free from the distractions of daily life.

This quatrain is a beautiful expression of the longing for a love that is pure and unconditional. It invites us to consider the importance of solitude and intimacy in our own lives.