“He is mad as a hare, poor fellow,
And should be in chains” you say,
I haven’t a doubt of your statement,
But who isn’t mad, I pray?
Why, the world is a great asylum,
And the people are all insane,
Gone daft with pleasure or folly,
Or crazed with passion and pain.

Ella Wheeler Wilcox (1850-1919) American author, poet, temperance advocate, spiritualist

Poem (1882), “All Mad,” st. 1, Maurine and Other Poems (1882 ed.)
    (Source)

Also collected in Poems of Cheer (1910) and Poems of Life (1919).