How poison came out when the milk ocean was churned?

Shri Bharath Krishna asked: Pādanamaskāram Swami, While reading Your knowledge I have got the following questions. Kindly answer these questions of mine. The milk ocean on which Lord Vishnu rests is assumed to be so pure. How can such a poison came out of it when it is churned? Why poison came first and then only Amrutam? Why not otherwise? Is there any hidden knowledge behind this story? If so, please tell me about it Swami.]

Swami Replied:- The poison came from the mouth of Vaasuki serpent and not from the ocean of milk. The happiness of good Sattvam quality is first poison and next divine nectar (Yattadagre viṣamiva, pariṇāme amṛtopamam, tat sukhaṃ sāttvikaṃ proktam, Ātmabuddhi prasārajam…- Gītā). The happiness of bad Rajas and Tamas qualities is first divine nectar and next horrible poison. Since this action was done by the advice of God, it belongs to the first category because God is very near and dear to Sattvam quality.