Felix Mendelssohn (1809-1847) was a German composer of the early Romantic period, and brother to fellow composer Fanny Mendelssohn. He wrote over 750 pieces of music in his lifetime including seven operas and thirteen symphonies. His most well-known work is the "Wedding March" from Shakespeare's A Midsummer Night's Dream, which is commonly played at wedding ceremonies in the Western world.
His "Spring Song," the sixth movement from Book 5 of his Songs Without Words, is commonly used in cartoons to audibly illustrate moments of lighthearted fancy. On Sesame Street, the tune was briefly used in "Elmo's World: Pets" to underscore Dorothy's imaginative depiction of what Elmo would look like as a bird swinging in a cage and "Elmo's World: Water" to underscore a little girl swimming with water wings for Dorothy.
The tune also is used to score some of the "Happy Girl Meets a Monster" sketch on The Ed Sullivan Show, and is woven briefly into "Froggy Went A Courtin'" in The Muppets Valentine Show.