Proclus was one of the major Greek philosophers of late Antiquity. In his metaphysics he developed and systematized problems of Plato's thought, such as participation; transcendence - immanence; causation - participation - return; henads and monads; first and second causality. Before and after his works had been translated into Latin, Proclus influenced the Christian West through the _Liber the causis_, a Latin translation of an anonymous Arab version of Proclus' _Elementatio theologica_.
These are two of only three medieval treatises known to the editors explicitly devoted to discussion of concepts. That is not to deny that other works treat extensively of concepts among other matters.
This anonymous source publication of a university discussion held in Prague about 1400 provides us with new information about medieval semantics after Peter of Spain and Richard Billingham. The edition is the basis of a partial reconstruction of Thomas of Cleves’ _Logica_.