Even though your office may be nearby, you can never be too confident, because even a short distance from your doorstep you may have a car accident. Nobody can tell what our destiny holds for us. You can even meet seemingly agreeable people in seemingly agreeable places, but the result is not necessarily good - it could even bring untold misery to you. Passing an examination may be the goal of people who study hard. But at the very moment that a person finds he has passed the exam, some tragedy could happen.
Nobody can tell.
Suppose there are a man and a woman who dearly love each other, and they are confident that they are going to live as the most ideal couple in the whole world. But right at the wedding ceremony, something unexpected may come about. From this we can gather that a man can never be too sure of having a bright future. But there are not too many things around us that hold such a promise for goodness. No one can be relaxed and reassured when he is all alone.