Humorists handle thoughts and ideas as golf or billiard champions handle their balls, or as cowboy champions handle their lariats. There is an ease, a sureness, a lightness of touch, that comes from mastery. After all, only he who handles his ideas lightly is master of his ideas, and only he who is master of his ideas is not enslaved by them. Seriousness, after all, is only a sign of effort, and effort is a sign of imperfect mastery. A serious writer is awkward and ill at ease in the realm of ideas as a nouveau riche is awkward, ill at ease and self-conscious in society. He is serious because he has not come to feel at home with his ideas.
— Lin Yutang, The Importance of Living
Actually, seriousness is not incompatible with joking. It’s a common mistake to confuse “serious” with “solemn,” and to assume that seriousness of purpose can only be conveyed by solemnity of tone. It’s an understandable error; we do have a marked tendency, we Anglo-Saxons, to answer the big questions with furrowed brow and down-turned mouth. An acquaintance of Dr. Johnson, on hearing of his reputation as a philosopher, remarked, “I have tried too in my time to be a philosopher, but, I don’t know how, cheerfulness was always breaking in.” But cheerfulness and thoughtfulness aren’t mutually exclusive. It’s simply wrong to assume that everyone who jokes about serious matters like death and pain is somehow failing to deal with them, that laughter is a childish, evasive response and that the only mature reactions are solemn, somber and po-faced.
Jimmy Carr & Lucy Greeves, The Naked Jape: Uncovering the Hidden World of Jokes