The Buddha contrasts the undeveloped and developed mind.
Akammaniya vagga - The Chapter On The Ineffective
1.21
"Bhikkhus, I do not see any other single thing that, when undeveloped, is as ineffective as the mind. An undeveloped mind is ineffective."
First.
1.22
"Bhikkhus, I do not see any other single thing that, when developed, is as effective as the mind. A developed mind is effective."
Second.
1.23
"Bhikkhus, I do not see any other single thing that, when undeveloped, leads to as much harm as the mind. An undeveloped mind leads to great harm."
Third.
1.24
"Bhikkhus, I do not see any other single thing that, when developed, leads to as much benefit as the mind. A developed mind leads to great benefit."
Fourth.
1.25
"Bhikkhus, I do not see any other single thing that, when undeveloped and uncleared, leads to as much harm as the mind. An undeveloped and uncleared mind leads to great harm."
Fifth.
1.26
"Bhikkhus, I do not see any other single thing that, when developed and cleared, leads to as much benefit as the mind. A developed and cleared mind leads to great benefit."
Sixth.
1.27
"Bhikkhus, I do not see any other single thing that, when undeveloped and not frequently cultivated, leads to as much harm as the mind. An undeveloped and infrequently cultivated mind leads to great harm."
Seventh.
1.28
"Bhikkhus, I do not see any other single thing that, when developed and frequently cultivated, leads to as much benefit as the mind. A developed and frequently cultivated mind leads to great benefit."
Eighth.
1.29
"Bhikkhus, I do not see any other single quality that, when undeveloped and not frequently cultivated, leads to as much suffering as the mind. An undeveloped and infrequently cultivated mind leads to great suffering."
Ninth.
1.30
"Bhikkhus, I do not see any other single quality that, when developed and frequently cultivated, leads to as much ease as the mind. A developed and frequently cultivated mind leads to great ease."
Tenth.