SN22.127 — Dutiyasamudayadhammasutta

At one time, Venerable Sāriputta and Venerable Mahākoṭṭhika were staying near Benares in the Deer Park at Isipatana. Then, in the late afternoon, Venerable Mahākoṭṭhika came out of retreat, approached Venerable Sāriputta, and sat down to one side. Venerable Mahākoṭṭhika said to Venerable Sāriputta:

Ignorance, ignorance, they say, friend Sāriputta. But what is ignorance, and how is one mired in ignorance?

Here, friend, an uneducated ordinary person does not truly understand form as a phenomenon that arises and passes away. They do not truly understand feeling as a phenomenon that arises and passes away. They do not truly understand perception as a phenomenon that arises and passes away. They do not truly understand choices as phenomena that arise and pass away. They do not truly understand consciousness as a phenomenon that arises and passes away. This is called ignorance, friend, and this is how one is mired in ignorance.