辅时：适应时势行事。违时：违背时势行事。当时：适时。圣人行事能够适应时势，不能违背时势。聪明人善于谋划，不如利用合适的时机。

Being brave isn’t the absence of fear. Being brave is having that fear but finding a way through it.

We are all ghosts of ourselves, haunting the places we once lived.

The beauty of topological insulators lies in their robustness; their surface states are protected by symmetry and topology, making them immune to certain types of disorder.