Meaning of the word "the longest journey is the journey within" in English

What does "the longest journey is the journey within" mean in English? Explore the meaning, pronunciation, and specific usage of this word with Lingoland.

the longest journey is the journey within

US /ðə ˈlɔŋ.ɡəst ˈdʒɜr.ni ɪz ðə ˈdʒɜr.ni wɪˈðɪn/
UK /ðə ˈlɒŋ.ɡɪst ˈdʒɜː.ni ɪz ðə ˈdʒɜː.ni wɪˈðɪn/
"the longest journey is the journey within" picture

Idiom

a philosophical proverb suggesting that self-discovery and understanding one's own mind and soul is the most challenging and extensive process a person can undertake

Example:
After years of traveling the world, he realized that the longest journey is the journey within.
Meditation taught her that the longest journey is the journey within.