Bhagavad Gita · Dhyana Yoga (Atma-samyama Yoga)Chapter 6, Shloka 34 (6.34)

Four epithets — an honest portrait of the mind.

Shankaracharya. First, the meaning of "Kṛṣṇa": kṛṣyateḥ vilekhanārthasya rūpam, bhakta-jana-pāpādi-doṣākarṣaṇāt kṛṣṇaḥ — from the root "kṛṣ" (to pull / to scrape); "Krishna" because He pulls away the sins and other faults of His devotees. The mind: pramāthi ca pramathana-śīlam pramathnāti śarīram indriyāṇi ca vikṣipat sat para-vaśīkaroti — it shakes up the body and senses and makes them dependent on something else; balavat … na kenacit niyantuṃ śakyam; dṛḍhaṃ tantu-nāgavat acchedyam — impossible to cut, like a "tantu-naga" (a water creature / like a tough rope); vāyor iva … tato'pi duṣkaraṃ manye — even harder than the wind.

Acharya Ramanuja. Anavaratābhyasta-viṣayeṣu api svata eva cañcalam — even among objects it is constantly used to, the mind is restless by itself; puruṣaṃ balāt pramathya dṛḍham anyatra carati — it forcibly shakes a person up and goes off somewhere else; so tad-viparītākāra ātmani sthāpayituṃ — to settle it in the self, which is its complete opposite, is pratikūla-gateḥ mahā-vātasya vyajanādinā iva suduṣkaram — as hard as stopping a gale blowing the other way with a hand-fan. Mano-nigrahopāyo vaktavya ity abhiprāyaḥ — Arjuna's intent: tell me the means of controlling the mind.