Describe Patrick Henry's importance of truth for his famous speech.

Patrick Henry's famous speech delivered at the Virginia House of Burgesses was a cry for liberty from tyranny. It focuses on the importance of truth, which is the only thing that will let the colonists truly debate whether freedom is worth the potential cost. His focus on truth also helps make his final appeal for freedom from tyranny more important, showing that he deeply means and believes what he says. 
Henry's speech was not recorded when it was made. His biographer later attempted to piece it together from accounts of people who were there, so there is no guarantee that the words are the exact ones Henry actually said. However, accounts say that he made an appeal for truth even when truth is painful. 
Henry says "in proportion to the magnitude of the subject ought to be the freedom of the debate. It is only in this way that we can hope to arrive at truth and fulfill the great responsibility we hold to God and our country." He is speaking of the issue of declaring independence from Britain. Henry means that people have to be forthright and open in the debate because it is an extremely important subject. Henry says that people seeking to hold back the truth in order to keep from offending others are as bad as those who commit treason. He also says that holding back the truth is an act of disloyalty toward God.
He goes on to explain that people often hide from unpleasant truths and choose to cling to more comfortable lies. He says that this is not the right course for wise men and that he would rather know the real truth, no matter how difficult it is or what the cost is to him. Henry says,

Mr. President, it is natural for man to indulge in the illusions of hope. We are apt to shut our eyes against a painful truth, and listen to the song of that siren till she transforms us into beasts. Is this the part of wise men, engaged in a great and arduous struggle for liberty? Are we disposed to be of the number of those who, having eyes, see not, and, having ears, hear not, the things which so nearly concern their temporal salvation? For my part, whatever anguish of spirit it may cost, I am willing to know the whole truth; to know the worst, and to provide for it.

This focus on the importance of truth helps explain his words at the end of the speech in which he says that life isn't important enough to put up with tyranny. He is underscoring the truth in his words in order to convince others how much he means what he is saying when he uttered the famous words: "Give me liberty or give me death."