Critolaus, of *Phaselis, head of the *Peripatetic school. His dates are unknown, but he was probably an old man when he took part, with *Carneades the Academic (see academy) and *Diogenes (3) the Stoic (see stoicism), in the philosophers’ delegation to Rome in 156/5 bce. His headship of the school marks a renewal of its scientific and philosophical activities. The fragments of his writings show some acquaintance with Aristotelian doctrines, though much of it may be second-hand. He defended the Aristotelian doctrine of the eternity of the world against the Stoic periodic conflagration, and taught that the soul was made of the fifth element, i.e. the heavenly aether. In ethics he held the highest good to be a composite of the goods of the soul, those of the body, and external goods, while emphasizing the far greater importance of the first. His criticisms of the Stoic distinction between ‘passions’ (πάθη) and ‘good feelings’ (εὐπάθειαι) reflect a general opposition to the monistic Stoic psychology.