Truth is concrete, which is determined by the objectivity of truth. It means that any truth, that is, the consistency between subjective and objective, is the consistency or conformity of the subject's understanding with a specific object within certain conditions and scope. If we go beyond these specific boundaries, as Lenin said, "One more small step and the truth will become wrong."

Usefulness is truth, which is obviously wrong:

(1) Truth is conditional, leaving the specific time, place and conditions. It is an idealistic view to talk about truth in the abstract.

(2) Truth is the synthesis of many essential provisions of things, and it is a metaphysical view to talk about truth unilaterally.

(3) Truth is historical and a process, and talking about truth statically is a metaphysical point of view.

(4) Truth is concrete, and monism of truth means the same thing, that is, at the same time and place, people can only have one understanding of the truth of the same thing, which varies from person to person and everyone is equal before the truth.