In 8 March 2007 Ernst von Glasersfeld attains the age of 90. In celebration of this, we take great pride in publishing this festschrift as our way of saying thank you, and of sending greetings and our affection to this remarkable, honest and modest man. A festschrift is a particular publication, and we have a particular approach. We require that in the all pieces we will publish, the work of von Glasersfeld will take centre stage. We also invite two types of contribution: the more normal academic paper, and more anecdotal pieces which carry a more personal message. We are grateful to our authors for helping us realise a festschrift that attains these aims. We add our thanks, too, to photographers, artists and poets who have enriched the von Glasersfeld related material we have been able to publish, which, we believe, enhances the general quality.