It would seem that happiness cannot be lost.  It seems that if you just make a lot of effort to keep a positive attitude, perhaps you can avoid losing happiness in life.  However, it seems kind of hard to always keep a positive attitude no matter what happens in life, so maybe one can even lose happiness when one stops maintaining a positive attitude? Well, indeed, there are a number of ways one can lose happiness according to Saint Thomas Aquinas.  Firstly, Aquinas says, that a person “…will no longer be truly happy if some evil exists in him.”(Treatise on Happiness, Saint Thomas Aquinas. Trans. John A. Oesterle. Notre Dame, Indiana: University of Notre Dame Press, 1983. P.59 from Summa Theologiae Question V. Art. 4)  That seems easy enough, no one wants to be unhappy, so the extrication of evil in oneself seems possible and everyone working on maintaining a positive attitude probably already realizes that they have their own faults which cause themselves or others to be negative around them.  So, that seems kind of evil, personal faults are negative and negativity can sure wreck a positive attitude so maybe happiness can be lost by the negativity brought on by faults, alone?  Well, not really.  According to Aquinas, in order to have true happiness, a person needs “an assured belief that he will never lose the good which he has.”(p.59)  In other words, a positive attitude is not sufficient, because a positive attitude rests upon “an assured belief.”  So, how can one lose happiness? According to Aquinas, happiness can be lost through a false belief.  He says, “…it is evil to have a false belief, for what is false is an evil for the intellect just as what is true is good for it.”(p. 59)  Well, this seems easy enough, nobody likes to be fooled by some false belief, and as Aquinas says, a false belief is evil for one’s mind, then it makes sense that in order to attain true happiness, all of our beliefs need to be true in order for us to be truly happy in life.  This seems true and not true at the same time, because true happiness is not found in this life alone.  Aquinas says, “The present life is subject to many evils which cannot be avoided:  the evil of ignorance on the part of the intellect, the evil of inordinate affection on the part of desire, and the evil of much suffering on the part of the body…”(p.57)  So, as “assured belief” pertains to our question of happiness being lost, so too we should be assured that just as this life is constantly changing, this constant change is an indicator of this life not being the perfect life which is not subject to time and change, which means that, as such, happiness can be lost in this life by false beliefs, excessive desires and lots of bodily pain.  He says, “A man’s will can change so as to fall into vice from virtue, in the act of which happiness principally consists.  Even if virtue remains untouched, external changes can disturb such happiness insofar as they hinder many acts of virtue; yet they cannot wholly take away virtue, so long as there still remain that act of virtue whereby man bears such adversities nobly.”(p.58)   Here, Aquinas makes it clear that virtue is key to all happiness and the total loss of virtue into vice assures us of unhappiness, lost happiness .  So, since everyone wants to be happy, it seems important that we should have assured belief and virtues to sustain us.  However, Aquinas adds to this and says, “All things seek to be conformed to God, as to an ultimate end and first principle”(p. 19) and that “…God cannot be in error…”(p.18), therefore, we can say that seeking God as a person’s unchanging ultimate end is the assured belief we would need in order for us to be truly happy. Well, what about this life?  Can we be truly happy now?  Aquinas says, “…what is good in the present life is transitory; for life itself, which we naturally desire, passes away, and we would like to hold on to it for ever, since man naturally shrinks from death.”(p.57)  The fact that the things of this life are fleeting is ever evident, wealth, health, joy, sorrows, loss of family members and friends in death, but Aquinas says “Some participation in happiness can be had in this life, but true and perfect happiness cannot be had in this life.”(p.57) Another big problem with true happiness in this life is that everyone is naturally scared to death of death which can be a huge distraction to maintaining happiness and a positive attitude.  However, the point of life is not to get hung up on the certain truth of our own personal death, which really is only a brief part of the experience of life, (and even Socrates made peace with his own death and with God before he died and he died basically peacefully even though he was poisoned to death).  Aquinas says “…the desires for good cannot be fully satisfied in this life, for man naturally desires the good he has to be permanent.” (p.57) This makes all kinds of sense, no one wants to lose happiness and the reality of death assures us of the reality that happiness in this life has a definite end point.  As Aquinas says, “…man naturally desires to hold on to the good which he has and to have the assurance of keeping it, otherwise he will be distressed by the fear of losing it or by sorrow in the certainty of losing it.”(p. 59) However, when we have assured belief, death is not a problem, merely a transition to, if we earn it, eternal happiness, a happiness that can never be lost, this is what Heaven is.   Aquinas says “the vision of the divine essence fills the soul with every good, since the soul is united with the source of all goodness.”(p.59)  Since the soul is filled with the very source of all goodness, this contemplation of the wisdom of God is what makes a person permanently happy, then we have to be free of every error in our character and every false belief in our mind in order to be intentionally united to the ineffable wisdom of God.  When we have this unity, it cannot  “…be taken away by another agent, for the mind united to God is raised above all other things and no other agent can separate the mind from that union.”(p.59)  Well, as we were speaking of earlier, it seems that it is the evil in us which makes us lose our happiness and as a consequence, we could be stung by the fear of losing the things we prefer to have in this life and then we are struck by sorrow with the definite loss of those things because of our attachment to them and not God.  But fortunately, no one else can take away our happiness if we are intentionally united with God’s will, only our attachment to our own will can cause us to have a false belief which is an evil that will make us unhappy.  So, assured belief is attachment to God’s will and, therefore, it is our own personal assured belief that is a necessary basis for our positive attitude in the first place because of the hopeful possibility of the total fulfillment of happiness in the next.  This is great news, assured belief in this life prevents us from losing imperfect happiness in this life and leads to happiness forever in the next life because of the union of our mind with the will of the omniscient God, now and forever.