Shloka 24

जीर्यन्ति जीर्यतः केशा दन्ता जीर्यन्ति जीर्यत: । चक्षु:श्रोत्रे च जीर्येते तृष्णैका न तु जीर्यते,मनुष्यके जीर्ण (जराग्रस्त) होनेपर उसके केश जीर्ण होकर झड़ जाते हैं, वृद्ध पुरुषके दाँत भी टूट जाते हैं, नेत्र और कान भी जीर्ण होकर अन्धे-बहरे हो जाते हैं। केवल तृष्णा ही जीर्ण नहीं होती है (वह सदा नयी-नवेली बनी रहती है)

jīryanti jīryataḥ keśā dantā jīryanti jīryataḥ | cakṣuḥśrotre ca jīryete tṛṣṇaikā na tu jīryate ||

Bhishma said: “As a person grows old, the hair withers and falls; the teeth too decay with age. The eyes and ears also grow feeble. Yet craving alone does not grow old—it remains ever fresh.”

{'jīryanti''they decay, they wear out', 'jīryataḥ': 'as (one) decays/ages
{'jīryanti':
in the state of aging (genitive/ablative sense used adverbially)', 'keśāḥ''hairs (of the head)', 'dantāḥ': 'teeth', 'cakṣuḥ': 'eye
in the state of aging (genitive/ablative sense used adverbially)', 'keśāḥ':
sight', 'śrotre''the two ears
sight', 'śrotre':
hearing (dual)', 'ca''and', 'tṛṣṇā': 'thirst
hearing (dual)', 'ca':
insatiable desire', 'ekā''alone', 'na': 'not', 'tu': 'but, however'}
insatiable desire', 'ekā':

भीष्म उवाच

B
Bhīṣma
T
tṛṣṇā (craving/desire)
K
keśa (hair)
D
danta (teeth)
C
cakṣus (eyes)
Ś
śrotra (ears)

Educational Q&A

Physical faculties inevitably decline with age, but craving (tṛṣṇā) can remain undiminished; therefore one should cultivate restraint and detachment deliberately, rather than assuming old age will automatically end desire.

In Anuśāsana Parva, Bhīṣma is instructing Yudhiṣṭhira on dharma and right conduct; here he offers a reflective maxim about aging to underscore the moral need to govern desire.