Then a certain bhikkhu approached the Blessed One, paid homage to him, sat down to one side, and said to him: “Venerable sir, it is said, ‘true knowledge, true knowledge.’ What is true knowledge, venerable sir, and in what way has one arrived at true knowledge?” sn.v.430
“Bhikkhu, knowledge of suffering, knowledge of the origin of suffering, knowledge of the cessation of suffering, knowledge of the way leading to the cessation of suffering: this is called true knowledge, bhikkhu, and it is in this way that one has arrived at true knowledge.
“Therefore, bhikkhu, an exertion should be made to understand: ‘This is suffering.’… An exertion should be made to understand: ‘This is the way leading to the cessation of suffering.’”