Śrīla Bhaktivinoda Ṭhākura informs us that this letter from Rūpa Gosvāmī to Sanātana Gosvāmī is mentioned by the annotator of the Udbhaṭa-candrikā. Śrīla Rūpa Gosvāmī wrote a note to Sanātana Gosvāmī from Bāklā. This note indicated that Śrī Caitanya Mahāprabhu was coming to Mathurā, and it stated: yadu-pateḥ kva gatā mathurā-purī raghu-pateḥ kva gatottara-kośalāiti vicintya kuruṣva manaḥ sthiraṁ na sad idaṁ jagad ity avadhāraya “Where has the Mathurā-purī of Yadupati gone? Where has the Northern Kośalā of Raghupati gone? By reflection, make the mind steady, thinking, ‘This universe is not eternal.’ ”