Bhagavad Gita Chapter 2, Verse 66

नास्ति बुद्धिरयुक्तस्य न चायुक्तस्य भावना । न चाभावयतः शान्तिरशान्तस्य कुतः सुखम् ॥

nāsti buddhir ayuktasya na cāyuktasya bhāvanā | na cābhāvayataḥ śāntir aśāntasya kutaḥ sukham ||

There is no discriminative intellect for the unsteady; nor is there contemplation for the unsteady. For one not contemplating, there is no peace. For the peaceless, how can there be happiness?

After showing the upward spiral in 2.64-65, Krishna now reveals the downward one. This verse shows why happiness feels impossible for some: they're ayukta (undisciplined, unsteady mind). Without rāga-dveṣa-viyukta from 2.64, the cascade fails: 'Nāsti buddhiḥ ayuktasya'—no steady intellect for the undisciplined. 'Na bhāvanā'—no sustained contemplation. 'Na śāntiḥ'—no peace. 'Aśāntasya kutaḥ sukham'—how can there be happiness without peace? You cannot skip steps. Want happiness? Build backwards: need peace. Want peace? Need contemplation. Want contemplation? Need steady buddhi. Want steady buddhi? Need discipline (rāga-dveṣa-viyukta). Foundation first, everything else follows.