C.S. Lewis had a gift for illuminating complex theological ideas. His 1952 book “Mere Christianity” is a defense of the Christian faith specifically, but its themes apply to life in a broader sense. Take this quote on moral responsibility, for instance. Here, the Irish-born writer states that doing the right thing raises the bar for ourselves. The more we exercise our moral muscles, the more they’re capable of and the more they require us to act accordingly. This may sound like a burden, but it’s quite the opposite: Ultimately, it shapes us into people capable of courage, integrity, and compassion for those around us.