Book 2, CHAPTER 6: The Joy of a Good Conscience
Comment: A good conscience brings joy on many levels – one that comes to mind is that you don’t have to remember lies or excuses that you told to cover some slight or omission or outright untruth.
Thomas compares joy with glory and develops some similarities where a good conscience is developed. Glory is fleeting and outward and vain unless it is driven by a love for the Cross. Whereas heavenly glory is grounded in a good conscience and truth. In striving for a pure conscience, you do not need to seek the recognition of others. Thomas subscribes to the notion that a disciple with a good conscience should seek to walk humbly with God.
Chapter 6, In Short.
1. Joy comes from keeping a good conscience.
2. To glory in tribulation is not hard for those that love; for such glory is found in the Cross of Christ
3. Those with a pure conscience will be contented and filled with peace.
4. The state of a spiritual disciple is to walk with God within.
Book 2, Chapter 6: The Joy of a Good Conscience
The glory of a good conscience is the testimony of a good man (2 Cor 1:12). Keep a good conscience and you shall always have joy. A good conscience 
is able to bear with interruptions, and is very joyful in the midst of adversities. An evil conscience is always fearful and unquiet. You shall rest sweetly if your heart does not condemn you (Prov. 3:24). Still, never rejoice unless when you have done well.
The wicked never have true joy, nor feel internal peace, for “there is no peace, says my God, to the wicked (Is 48:22).” And if they say “we are in peace, no harm shall befall us, and who shall dare to do us harm?” do not believe them, for the wrath of God may suddenly rise up against them, and their deeds shall be brought to nothing, and their projects shall perish.
2. To glory in tribulation is not hard for those that love; for such glory is found in the Cross of Christ (Gal. 6:14). That glory is short-lived which is given and received by others. The glory of the world is always short-lived and accompanied by sadness and great sorrow. The glory of the good is in their conscience, and not in the mouths of others. The joy of the upright is from God and in God, and their joy is in the truth (1 Cor. 13:6).
Whoever desires true and eternal glory does not care for that which is temporal; and whoever seeks such worldly glory, or does not reject it from the heart, is proved to bear little love for that which is heavenly. The disciple who cares for neither praises nor reproaches has great tranquility of heart.
3. A disciple whose conscience is pure will easily be contented and filled with peace. You are none the holier if you are praised, nor less saintly if you are reproached. You are what you are; and you cannot be better than God pronounces you to be.
If you consider well what you are inwardly, you will not care what others say to you. The world looks to outward appearances, but the Lord looks at the heart (1 Sam 16:7). Mankind considers the action, but God considers the intention.
It is the token of an humble spirit always to do well, and to set little account by one’s self. To refuse comfort from any created thing is a sign of great purity and inward faithfulness.
4. The disciple that does not seek an outward testimony for himself shows plainly a full commitment to God. As St. Paul says, “For it is not the one who recommends himself who is approved, but the one whom the Lord recommends.”(2 Cor. 10:18)
To walk with God within and not to be held by any outer affections, is the state of a spiritual disciple (Mi. 6:8).