Bhagavad Gita 2.67
इन्द्रियाणां हि चरतां यन्मनोऽनुविधीयते । तदस्य हरति प्रज्ञां वायुर्नावमिवाम्भसि ॥
indriyāṇāṃ hi caratāṃ yan mano 'nuvidhīyate | tad asya harati prajñāṃ vāyur nāvam ivāmbhasi ||
Translation
For the mind which follows the wandering senses carries away the understanding, as the wind carries a ship on the waters.
Reflection
Which one sense has been steering your day when you thought your mind was?
Read this verse in its chapter: Chapter Two
The image of the chapter's second half. Vāyuḥ nāvam iva ambhasi. As wind carries a ship across the waters. One sense, going its own way, can capture the mind. The mind, captured, carries the prajna, the understanding, off course. The verse is structural: the sthita-prajna of 2.55 onward is sthita, steady, exactly because the mind has stopped being moved by the wandering of a single sense organ. The wind on the water is small; the consequence is total. The verse names a small leak with a large effect.