The inimitable Van Reid pointed this one out to me. Patrick McDonnell is known for the way he salutes cartoonists he respects and admires. This Mutts Christmas strip from 2007, albeit wonderfully zen in its own right, turns out to be nothing less than a graphical quotation and hommage to a similar Gasoline Alley Christmas strip by Frank King from 1930.
Somebody should do a index of these things.
(Mutts © 2009 Patrick McDonnell. Gasoline Alley © 2009 Universal Press Syndicate. And thanks again to Van Reid)