Prabhupāda: That is called mano-dharmī. In Sanskrit it is called mano-dharmī, mental speculators.
Prajāpati: It's a disease, actually.
Prabhupāda: And therefore, mental speculators, they have been condemned. Manorathenāsati dhāvato bahiḥ (SB 5.18.12). Because they carry on, or they are carried by the chariot of mind, manorathena. Manorathena asati. Manoratha, when you drive on the chariot of mind, you cannot get any fixed idea. Because mind is flickering. Saṅkalpa-vikalpa. Mind's business is "Accept this, and again reject it." So all these speculators are doing. Somebody is putting forward some theory, and after some years he will himself reject or somebody else will reject. So manorathena, by mental speculation, you remain on the material platform. You cannot get any spiritual idea.