This volume is a collection of articles by Filippo Motta, professore di glottologia e filologia celtica at the Università di Pisa, on the occasion of his retirement. It assembles twenty-one articles from almost forty years of research. It is a fundamental issue of honouring collections like this one that much of the contents may have been overtaken by new insights in the meantime. The earliest contributions in this volume appeared more than forty years ago, and most are at least twenty years old. This is at least one academic generation. Even in a small, seemingly slow-moving discipline such as Celtic Studies, important progress comes now at the pace of a couple of years, if not months. There is no longer the comfort of relying on data and its analysis of decades or generations ago. For that reason, it is often the methodology demonstrated in the contributions in this volume that is the lasting contribution, while conclusions and results themselves may have been superseded by newer ones.