1. the relationship between time and environment: this sentence may refer to the influence of environment on wolves and rabbits in the morning and evening. In some cases, the environment may be drier and colder in the morning and wetter and warmer at night. This environmental change may affect the behavior of wolves and rabbits, making it easier to see wolves in the morning and rabbits at night.
2. moral: this sentence may also be moral, indicating that something will have different results or situations sooner or later. For example, one thing may be difficult at first, and then it becomes easy; Or it looks promising in the morning and difficult at night.
In a word, the specific meaning of this sentence will vary with different regions, cultures and personal understanding.