Isolation. That is the deepest loneliness.
But there are other kinds.
There is the lonely that isn't always so bad. There is the lonely of knowing that no one else believes what you believe where you are. That you live in a world of confusion and darkness. That your little light is pressed and crushed by the blackness.
I wrote this poem a long time ago while thinking of this. And it seems to go well with these thoughts:
My little flickering candle, small and humble yet so clear,
Wavers meekly in the darkness as I hesitate in fear.
My flame-it weakens as the blackness presses in so near.
Oh, if only I knew that I was part of a giant chandelier!