For one whose mind is unsteady, and who does not understand the true Dhamma; For one whose confidence wavers, wisdom does not reach fullness.

–DhammaPada Verse 38

For one whose mind is not agitated, and whose thoughts are not afflicted; For one who has abandoned merit and demerit, there is no fear for the alert.

–DhammaPada Verse 39

Picture: Sunset at Montmajour, Vincent van Gogh, 1888

Related Teachings:

Importance of cultivating wisdom (AN 76 - 81) - A series of short teachings of the Buddha highlighting the importance of cultivation of wisdom.

Eight causes leading to wisdom (AN 8.2) - Eight conditions that lead to the arising of wisdom, its growth and perfection.

The Path and the Way of Practice for removal of five lower fetters (MN 64) - In this teaching, the Buddha shares the path and the way of practice for removal of the five lower fetters of: 1.) self-identity view, 2.) doubt regarding teachings, 3.) adherence to rites and rituals, 4.) sensual desires, and 5.) ill-will.