The science or art of exact reasoning, or of pure and formal thought, or of the laws according to which the processes of pure thinking should be conducted; the science of the formation and application of general notions; the science of generalization, judgment, classification, reasoning, and systematic arrangement; correct reasoning.
Logic will get you from A to B. Imagination will take you everywhere. Albert Einstein
Mathematics as an expression of the human mind reflects the active will, the contemplative reason, and the desire for aesthetic perfection. Its basic elements are logic and intuition, analysis and construction, generality and individuality. Richard Courant
When dealing with people, remember you are not dealing with creatures of logic, but creatures of emotion. Dale Carnegie
Nature is the source of all true knowledge. She has her own logic, her own laws, she has no effect without cause nor invention without necessity. Leonardo da Vinci
Chess helps you to concentrate, improve your logic. It teaches you to play by the rules and take responsibility for your actions, how to problem solve in an uncertain environment. Garry Kasparov