In plain words
Amutaṉār: On that day [when he drove Arjuna's chariot] the Lord of all dear souls, who bears the mighty discus, discerned the bright meaning hidden in the ocean of the Veda's words and gave it [through the Gītā]. Even after that, the people of the earth sank into the distress [of saṃsāra]; so our Rāmānuja, taking that same bright meaning, goes after them in their wake. This is his nature.