I. The example of the martyrs is most valuable
Whilst the height of all virtues, dearly-beloved, and the fullness of all righteousness is born of that love, wherewith God and one's neighbour is loved, surely in none is this love found more conspicuous and brighter than in the blessed martyrs; who are as near to our Lord Jesus, Who died for all men, in the imitation of His love, as in the likeness of their suffering. For, although that Love, wherewith the Lord has redeemed us, cannot be equalled by any man's kindness, because it is one thing that a man who is doomed to die one day should die for a righteous man, and another that One Who is free from the debt of sin should lay down His life for the wicked: yet the martyrs also have done great service to all men, in that the Lord Who gave them boldness, has used it to show that the penalty of death and the pain of the cross need not be terrible to any of His followers, but might be imitated by many of them.
If therefore no good man is good for himself alone, and no wise man's wisdom befriends himself only, and the nature of true virtue is such that it leads many away from the dark error on which its light is shed, no model is more useful in teaching God's people than that of the martyrs. Eloquence may make intercession easy, reasoning may effectually persuade; but yet examples are stronger than words, and there is more teaching in practice than in precept.
Source: Sermons (New Advent)