“You can never be lonely if you experience your aloneness as all-oneness.” – (Inspirational Thoughts: A Compilation of Wonderful Quotations for Your Personal Growth by Tycho Photiou, p.39).
Osho, recounting the parable of Lin Lei in The Book of Lieh Tzu: A Classic of Tao (translated by A.C. Graham, 1990), explains that people feel lonely because they have not yet created a relationship with themselves. They have yet to fall in love with themselves:
“I think a person needs to learn from childhood to find himself alone. It means to not be bored when you’re by yourself, because a person who finds himself bored when alone – as it seems to me – is in danger.” - Andrei Tarkovsky, A Poet in the Cinema.