As one move ahead in his path he becomes aware of the fact that, many things what we consider as truth and hold on to it, becomes meaningless. We have to hold on to the formless witness of the three states, not the three states which are mere illusion. Mentally holding on the formless witness and by negating the three states as illusion, then the witness alone will prevail.
Truth which has no basis is usually religion or a mere catalogue of ignorant opinions; people prefer it because it can be got more easily. A religious philosophy based on the physical self/ego is worthless from the standpoint of truth.
Truth is incomplete and inaccurate without reasoning. Truth means certain and exact knowledge. The science which limits it to its practical applications such modern machines, are wrong because science is only physical based wisdom. There is no need to learn any practical science in order to get the ultimate truth. Science is very helpful to give more comforts for mankind. But the ultimate truth is beyond physical based science. But one has to have certain knowledge of the fact that, the self is not physical before indulging in pursuit of truth.
Only through reason based on the soul as self one gets the exactness and certitude of knowledge therefore he acquires the Self-Knowledge/Non-dual wisdom. When one has an exact and certain knowledge of un-contradictable truth he can utilize it for the guiding the fellow seekers. The people who assume without any proof, have untrained reason.