Rien Poortvliet was a Dutch draughtsman and painter/illustrator. He was best known for his drawings of animals and for "Gnomes" in the famous series of books provided with text by Wil Huygen and published by Harry N. Abrams, Inc. of New York City. (Wikipedia) Gnomes are one of a species of diminutive beings, usually described as shriveled little old men/women, that inhabit the interior of the earth and act as guardians of the Earth and all its treasures.