Lord Krishna has delighted many devotees. Periazhvar, thinking of Krishna's birth, goes back in time to the period before Krishna's appearance as Devaki's son.
He says Krishna should not be born as her son. She has already lost seven of her children. What is the guarantee that Krishna will survive, if he is born to her? He prays that the Lord should go directly to Gokula. Periazhvar did not live in the time of the Krishna avatara. But he goes back in time, and imagines the birth of Krishna. A staunch devotee though, Periazhvar momentarily forgets that Krishna is the Parabrahma and he himself is born to serve the Lord. He is full of concern for the Lord's welfare.
It was this kind of concern that made Periazhvar sing blessings to the Lord, said Damal Ramakrishnan in a discourse.
A devotee of the Lord is bound to envy Kausalya, who bore Lord Rama; the pillar from which the Lord came forth as Narasimha; and Devaki, who gave birth to Krishna.
Andal, in her Thiruppavai, says Krishna was not raised by His mother but by another woman. But she refrains from naming either Devaki or Yashoda.
There was a reason for this. Like her foster father Periazhvar, Andal too bore immeasurable love for the Lord. And like her father, she too had a parental concern for the Lord.
Forgetting that she did not live in the time of Krishna and that the Krishna avatara had been taken and had also come to an end aeons ago, she fears for Krishna's safety. She is afraid that if she mentions the name of Devaki or Yashoda, Kamsa will cause harm to the baby Krishna. Andal had also been told the story of Krishna by her father, and he had only told her of Krishna's birth cryptically.
He had said Krishna was born 10 days after the star of Hasta. And Andal replied that she understood what her father meant. If we count in one direction from Hasta, the tenth star is Sravana, which is the star of Lord Narayana.
If we count in the other direction from Hasta, we get Rohini, which is the star of Krishna. So she has gathered that Krishna is none other than Lord Narayana.