Life is much too important a thing ever to talk seriously about it.

Oscar Wilde (1854-1900) Irish poet, wit, dramatist

Vera; or, The Nihilists, Act 2 [Prince Paul] (1881)
    (Source)

Almost always paraphrased, "Life is too important to be taken seriously."

In Lady Windermere's Fan, Act 2 (1892), he recycled the line as "Life is far too important a thing ever to talk seriously about it."

Also (mis)attributed to G.K. Chesterton. More discussion of this quotation: Life Is Too Important To Be Taken Seriously – Quote Investigator.