I wish you much happiness and health on your 90th birthday year. We all fondly remember the celebrations of your 50th birthday anniversary forty years ago (so far away and yet so present), when I was a newly arrived graduate student at the Linguistics Department at MIT. The research project that you and Morris had outlined for the field continues to fascinate me today as much as it did back then. As I look back, I believe we have made much progress. Although we understand little about language evolution, we now have the basic concepts that allow us to give meaningful descriptions of old and new phenomena, and the ability of discerning the arbitrary from the principled aspects of language. I would like to take this opportunity to thank you for so many decades of inspiring work and lectures that have made this progress possible.