In Einstein's words:

...creating a new theory is not like destroying an old barn and erecting a skyscraper in its place.  It is rather like climbing a mountain, gaining new and wider views, discovering unexpected connections between our starting point and its rich environment.  But the point from which we started out still exists and can be seen, although it appears smaller and forms a tiny part of our broad view gained by the mastery of the obstacles on our adventurous way up.

Quoted in "The Dancing Wu Li Masters: An Overview of the New Physics" by Gary Zukav