Śrīmad-Bhāgavatam · Text 11.21.10
Who is speaking and story frame
द्रव्यस्य शुद्ध्यशुद्धी च द्रव्येण वचनेन च ।
संस्कारेणाथ कालेन महत्वाल्पतयाथवा ॥ १० ॥
dravyasya śuddhy-aśuddhī ca
dravyeṇa vacanena ca
saṁskāreṇātha kālena
mahatvālpatayātha vā
An object’s purity or impurity is established by application of another object, by words, by rituals, by the effects of time or according to relative magnitude.
Read the purport on Vedabase.ioFrom Canto 10, chapter 14 onward, the translation and purports were completed by Śrīla Prabhupāda's disciples after his departure, and published by the Bhaktivedanta Book Trust.