Immanuel Kant said the following words:
1. "There is something splendid about innocence, but what is bad about it. In turn, is that it cannot protect itself very well."
2. "The reading of all good books is like a conversation with the finest minds of past centuries."
3. "To be is to do."
4. "Dare to know."

Albert Einstein said:
1. "Learn from yesterday, love for today, hope for tomorrow. The important thing is not to stop questioning."
2. "I think and think for months and years. Ninety-nine times, the conclusion is false. The hundredth time I am right."
3. "Imagination is everything. It is the previous of life’s coming attraction."
4. "Life is like riding a bicycle. To keep your balance you must keep moving."

The words of above two persons can be applied to our daily life. In our life, we will face many cross-roads which need our wisdom to decide what is the right direction to go forwards.
If we go a wrong way, we need to turn back. But we cannot turn back our middle age to young age. We can only go forward to old age which is the cycle of our life.