Abstract
This book contains twenty-two papers by K. Ajdukiewicz, an outline of his memoir and philosophical evolution by J. Giedymin, and a bibliography of Ajdukiewicz’s works compiled by T. Czezowski. In the colorful introductory paper, Giedymin characterizes the personality of the famous Polish philosopher-logician as a person open not only to philosophical investigations but also to contemplation of the beauty contained in music, literature, and nature. The sketch of Ajdukiewicz’s scientific activity presents him as an excellent teacher, open-minded in understanding different viewpoints but simultaneously as an independent and uncompromising thinker.