I have long maintained that in the unfolding of exciting lines of research, seldom can one plan how to achieve a cooperative program. “Planned science,” more often than not, is forced science and not particularly productive. Far more significant is the role of serendipity in defining an exciting and innovative line of research, i.e., a truly stimulating cooperation. Fundamental advances simply cannot be planned for; one has to flow with the current. Thus it was that serendipity brought together the research group in Experimental Embryology of Prof. dr. J.A.M. van den Biggelaar at the University of Utrecht, and my own group in Systematics and Zoogeography at the University of Amsterdam. Several years ago I had received a grant proposal to review from the Dutch science research council (NWO). The proposed project intended to examine patterns of early development in the gastropod Patella in a large scale, evolutionary context. I found the project an exciting one and gave it my highest endorsement. Furthermore, so taken was I by the proposal that I made contact with its author. Prof. van den Biggelaar. I had long entertained the idea that a combination of an evolutionarily inclined group in embryology with embryologically sensitive systematists could achieve great things. I revealed myself to Jo van den Biggelaar as one of his reviewers and proposed that we meet.