'Tava-kathamrtam tapta-jivanam' - is a couplet from the Gopika Gitam of Srimad Bhagavatam, rendered with rhythm by Swami Ramachandrananda Maharaj. Mahendranath Gupta, popularly known as 'M', used this couplet as the Invocation of Sri Ramakrishna Kathamrta, The Gospel of Sri Ramakrishna.