Prabhupāda: This is idea. Mano-rathena, by mental speculation, asato dhavato, they will come to materialism. As soon as they will hover over mental concoction, they will remain in the material pool, because mind is subtle form of matter.
Acyutānanda: Also, in their evidences by which they base their dialectic discussions, have they regarded the Vedic scriptures? They have avoided them very conveniently.
Prabhupāda: No, there is no question of dialectic discussion. Suppose I am discussing, you are discussing something, but if I am imperfect, you are imperfect, what is the value of such discussion? That is the point. The party discussing something, whether he is perfect? If he is not perfect, then go on discussing. We first of all say that any conditioned soul is defective, and that is admitted. They say, "We are not perfect." "I think," they say. "In my opinion," they say. Never they say, the so-called scientists, "definite." And they cannot say it.
Mahamsa: That is like Dr. Frog's philosophy when they speculate.
Prabhupāda: Yes. Simply speculation. So that kind of discussion, what is the value?