They should be allowed to play in dirt.
They should dump a huge bucket of toys to find the perfect miniature character to fit the complicated plot unfolding from their imaginations (as long as they clean it up later).
I believe that a baby should be able to pour however many cups of water it takes onto their belly for them to figure out how a cup works.
I think it's okay to walk through mud barefoot.
I believe that it is perfectly acceptable to feed a tired baby saucy ravioli even if it gets smeared on his or her head.