"The essence of mathematics lies in its freedom."
When you open your heart to positivity, you open your mind to possibilities.
The attosecond timescale is to electron motion what the high-speed camera was to studying animal locomotion.
应对不自由世界的唯一方法是变得如此绝对自由，以至于你的存在本身就是一种反叛。
A teacher must have a healthy body, the skills of a farmer, the mind of a scientist, the interest in art, and the spirit of social reform.