1.
The Discourse on the Teacher
73.
He was dwelling at Sāvatthī, etc.
"Monks, by one not knowing, not seeing ageing and death as it really is, for knowledge of ageing and death as it really is, a teacher should be sought;
by one not knowing, not seeing the origin of ageing and death as it really is, for knowledge of the origin of ageing and death as it really is, a teacher should be sought;
by one not knowing, not seeing the cessation of ageing and death as it really is, for knowledge of the cessation of ageing and death as it really is, a teacher should be sought;
by one not knowing, not seeing the practice leading to the cessation of ageing and death as it really is, for knowledge of the practice leading to the cessation of ageing and death as it really is, a teacher should be sought."
The first.