Since some of life's, and the world's greatest challenges can be solved with common sense, what is common sense? If the answer does not jump out of your mind, you are not alone. None of the hundreds of those surveyed by the author were able to answer with a high degree of certainty. So, this begs the question, why do we all agree that common sense is extremely important, yet so few of us can explain what it is? Since it is such a commonly used phrase, and many have accused others of lacking in it, it is reasonable to expect that we would all be able to explain what it is. It is reasonable, also, to assume that those of us who use it, but cannot explain what it is, could be using it incorrectly. Once you examine this phrase, "common sense", within the context of this research, you may agree that it is virtually a scientific principle, and that if it governs our ideas, knowledge, reasoning, and actions, it would guarantee that we would perform at our best. You may also conclude that common sense is far superior to academic learning and that, if it is applied, it can be the most effective tool for shedding light on all of life's challenges. Common sense is not a list of pronouncements to follow, but a logical process of thinking that lifted Western civilisation from its worse period of regression between 500 and 1000 AD, and is therefore instrumental to our current stage of advancement. Yet, despite this, we are far from being at our best, because we do not consistently use common sense to decipher our daily life challenges. This book takes the reader on a journey of how to navigate some of life's greatest challenges, and demonstrates how we can solve some of our seemingly intractable problems with the effective application of common sense.