Discovery of something the rest of the world already knows is still a valuable discovery

This is an obvious fact – we celebrate children learning to walk, read, etc.

But we sometimes forget to apply it to ourselves.

It is a natural pair to the notion that Ideas are not knowledge until they are tested or experienced.

From Democracy and Education:

Only silly folk identify creative originality with the extraordinary and fanciful; others recognize that its measure lies in putting everyday things to uses which had not occurred to others. The operation is novel, not the materials out of which it is constructed. The educational conclusion which follows is that all thinking is original in a projection of considerations which have not been previously apprehended. The child of three who discovers what can be done with blocks, or of six who finds out what he can make by putting five cents and five cents together, is really a discoverer, even though everybody else in the world knows it. There is a genuine increment of experience; not another item mechanically added on, but enrichment by a new quality. The charm which the spontaneity of little children has for sympathetic observers is due to perception of this intellectual originality. The joy which children themselves experience is the joy of intellectual constructiveness–of creativeness, if the word may be used without misunderstanding.