The medieval tune in Obrecht’s Renaissance masterpiece, the grandiose Missa Maria Zart was magnetizing composers for centuries, let’s just mention László Vidovszky’s adaptation for string quartet, as one of the most recent examples. It’s secret lies most likely in its fatal straying to Phrygian, eventuating quasi inevitably in the end of the work. The present series of variations attempts to evoke its subject, while the question, as to what the subject is, still remains unanswered. The composer and performer explore the secrets, depths, and actuality of the work through illustrated analysis – from the point of view of both performer and composer.