Sometime in the latter half of the 1920's, J. R. R. Tolkien purchased a postcard reproducing a painting by Josef Madlener called Der Berggeist (The Mountain Spirit). It shows an old man with a broad-brimmed hat and a red cloak, petting a white deer that nuzzles his hand; they are near a tiny stream in a tree-lined, airy, mountainous valley. Years later, on the paper cover in which he carefully preserved this picture, Tolkien wrote "Origin of Gandalf." This postcard, by a German painter of a figure from German folklore, was the jumping-off place for Tolkien's imagination, and the seed for the image of the most recognizable wizard (after Merlin) in all Western literature.
But it was, of course, just a starting spot; Tolkien did not use the personality of Rubezahl (as the Mountain Spirit is known) or Madlener's design or color scheme exactly. Here is how Tolkien describes Gandalf as he is first seen in The Hobbit: "All that the unsuspecting Bilbo saw that morning was an old man with a staff. He had a tall pointed blue hat, a long grey cloak, a silver scarf over which his long white beard hung down below his waist, and immense black boots." This is the figure that Tolkien produces exactly in his only full color sketch of Gandalf that has been published to date. This picture is of particular interest in that it gives some idea of the height of the hat and the length of the staff as Tolkien envisioned them. I believe the use of the blue hat and the grey cloak might have their origins in the appearance of Odin the Wanderer; this is how the Norse sky-god disguised his appearance when he travelled unknown among men. And this is Gandalf before he was called Gandalf the Grey. That title is only developed in The Lord of the Rings, and distinguishes him when he is considered as a member of a high and noble Order. Here his monochromatic ensemble is accented by touches of blue, silver, and black.
Years later, in The 1984 J. R. R. Tolkien Calendar, in the illustration for November, Roger Garland produced a painting that is surely a re-imagining of the Madlener postcard in a more exacting Middle-Earth context. Here Gandalf (though his beard is not so long as Tolkien describes, and his boots are yellow) sits by a small stream in a tree-lined, airy, mountainous valley. There is a deer (a stag, in fact) in the background; its distance, especially in contrast with the original, seems to emphasize the wizard's isolation as he travels on his mission, although his contemplative air as he surveys the beautiful scene could indicate that he is considering what is at stake on that task.