In a famous passage of Plato’s Sophist (248e-249a), The Stranger addresses the question of the activity of the perfect being: is it deprived from change, life, soul and understanding? Does it stand immutable, holy and solemn (semnos), devoid of intellect? There is an issue about whether this text is to be taken seriously. The present article analyses how this passage (and especially the word semnos) has been read after Plato, mainly by Plotinus but also by Aristotle (and hypothetically by Epicurus). In particular, it is argued that, despite its obscurity, the idea of solemnity plays a major role in Plotinus, but with different purposes, depending on the context, and in an ambiguous way. Generally speaking, the legacy of Plato’s passage is much more a question (is it possible to deprive that which is perfectly real from activity?) or even an aporia than a positive claim regarding the properties of being. This is probably the best way to read the passage, and to take it seriously.