This is the 4710th most frequent Chinese word.
真谛
The ultimate truth or essence.
In this sentence, "真谛" conveys the central or most essential aspect of life, which is true friendship.
真正的友谊是生活的真谛。
True friendship is the essence of life.
Here, "真谛" describes the fundamental meaning or core understanding regarding success.
通过艰难困苦，我们终于领悟了成功的真谛。
Through hardships and challenges, we finally understood the essence of success.
"真谛" in this sentence is used to describe the intrinsic quality or truth in the concept of art.