Doctors give medicine and they speak surety, but there is no surety, and when there is no surety why should we break our four basic principles? I don't think there is guarantee of surety by taking this medicine with animal products. But if there is surety, you can take. But it is very doubtful. When I shall come there I shall see what is wrong.
Letter to Govinda dasi, 12 February, 1972