Seneca emphasises that philosophy is to be lived
Zenonem Cleanthes non expressisset, si tantummodo audisset.
Cleanthes would not have imitated Zeno if he had merely heard him
Zenonem: Zeno (accusative singular)
Cleanthes: proper noun (nominative singular)
Non: not
Expressisset: would have imitated
Si: if
Tantummodo: only, merely
Audisset: had heard
