What is "of a truth"

Truth \Truth\, n.; pl. Truths. [OE. treuthe, trouthe, treowpe, AS. tre['o]w?. See True; cf. Troth, Betroth.]

1. The quality or being true; as:

   1. Conformity to fact or reality; exact accordance with that which is, or has been; or shall be.

   2. Conformity to rule; exactness; close correspondence with an example, mood, object of imitation, or the like.

      Plows, to go true, depend much on the truth of the ironwork.
      --Mortimer.

   3. Fidelity; constancy; steadfastness; faithfulness.

      Alas! they had been friends in youth, But whispering tongues can poison truth.
      --Coleridge.

   4. The practice of speaking what is true; freedom from falsehood; veracity.

      If this will not suffice, it must appear That malice bears down truth.
      --Shak.

2. That which is true or certain concerning any matter or subject, or generally on all subjects; real state of things; fact; verity; reality.

   Speak ye every man the truth to his neighbor.
   --Zech. viii. 16.

   I long to know the truth here of at large.
   --Shak.

   The truth depends on, or is only arrived at by, a legitimate deduction from all the facts which are truly material.
   --Coleridge.

3. A true thing; a verified fact; a true statement or proposition; an established principle, fixed law, or the like; as, the great truths of morals.

   Even so our boasting . . . is found a truth.
   --2 Cor. vii. 1

4. 4. Righteousness; true religion.

   Grace and truth came by Jesus Christ.
   --John i. 17.

   Sanctify them through thy truth; thy word is truth.
   --John xvii. 17.

   In truth, in reality; in fact.

   Of a truth, in reality; certainly.

   To do truth, to practice what God commands.

   He that doeth truth cometh to the light.
   --John iii. 21.