C'thia means logic, truth-reasoning, the way things are. Logic is actually the translation of the vulcan word, and is not fully adequate to the real meaning. C'thia is to think logically, rationally, and to have control of ones emotions. C'thia can be defined as Suraks teachings, but other things should also belong to c'thia, because Surak lived almost 2000 years ago. One can't know every single possibilty. One have, however, the ability to collect knowledge and often predict the outcome of an event. By continously learn, and think logical, one will more often find the solution. It is emotions that prevent people from thinking logical all the time. Thousands of years ago, the Vulcans were a people of war and violence. Then, suddently, 1700 years ago, the Vulcan Surak started to teach the Vulcans the way of thinking logical, reasonable, and peaceful, and thus making the wars something that only belonged to the past. His logical and peaceful way became his death, and he was killed without showing fear, or hate, or rage. His teachings started to spread, and others followed the way that Surak had shown them. It was succesful, because the number of followers increased, and the people of Vulcan became a logical people. There was, however, a group of Vulcans, later known as Romulans, that rejected new philosophy, and they left the planet. There is one thing that can prepare one for dangers, and helping one to succed in overcoming them, and that is knowledge. Therefore, one must learn. But without logic, with whiches help one can analyse the raw data, the knowledge is indeed not very useful. Humans have both knowledge and at least some logic -- at least some have the latter, and there aren't to many of them that have sufficient knowledge. In order to solve an equation, one must have the knowledge about solving one, because, without knowing how, one can't solve it. One must also be able to think logical, to reason, in order to perform the task. Emotions is that which prevents one from thinking logical. Emotions have their origin from the time when we were living in caves and hunting animals, and the time before that. Then, they were neccesary. E. g. when a dangerous animal were attacking a cave-man, he became afraid, and he perhaps ran away. When one become afraid, adrenaline is pumped out to the blood. Now the caveman could run faster and longer, or -- if he tried to do that -- fight the animal more efficient. The emotions filled a funktion that time, but now, with the greater intellect the humans have developed, they are no longer nessecary. Infact, they are damaging us. If captain Kirk pulled out his phaser every time he got angry -- well, let us just say that the Enterprise would no longer have a crew of approximately 400 people. A modern human would, at least some of them, use more sophisticated methods to overcome the problem with the dangerous animal than to run or attack. Perhaps use stones or sticks do defend himself (still on the cave-stage). Perhaps run away and make a trap for the animal. Perhaps make the animal damnage itself, by for example make it fall in a hole in the ground. This is what one can say about emotions: Emotions makes one loose control of ones thoughts, and occupates ones mind too often in the wrong moments. Emotions also makes one do illogical and harmful things that is often unneccesary, and only increases the amount of problems that one already have. Think about the mind as a sea, and the process of thinking as driving a boat on that sea. Then, obviously, emotions are waves on that sea. The emotions makes thinking slower, and more difficult, and sometimes the waves are so high that the boat can't go forward. Meditation is something that Vulcans are not unfamiliar with. It is meditation that can bring them their powerful control of thoughts and emotions.