Actually the rot set in later. The Lyceum was quite lively; for example, his lesser known colleague and co-worker Theophrastos was said to have had 2000 pupils, and others went on to create the fields of mechanics and pneumatics. His ideas influenced all subsequent ancient schools, and Arab scholars translated all his works they could find. His light dims in the west with the decline of the Roman Empire, until the Renaissance, when we find people like Leonardo da Vinci using his work on colours, which had survived or been recovered via Arabic scholarship.That Aristotle knew a thing or two. Shame so few paid attention to him while he was alive.