When Yan Hui died, Confucius wept for him in extreme grief.
Tips
history
恸 almost never stands alone in modern Chinese; it lives on in the literary compound 悲恸 ('grief-stricken') and the set phrase 恸哭 ('to wail'). The example is the famous line from the 《论语》 on Confucius mourning his disciple Yan Hui.
register
Literary. In speech people say 痛哭 or 悲痛; 恸 stays in written and classical registers.
动 supplies the sound for 恸, with the initial and tone drifting. A faint sense of the heart being violently 'moved' by grief fits but is secondary to the phonetic role.
