Don't let go too soon, but don't hold on too long.
不要太快放手，也别紧握太久。
It is inevitalbe to encounter with some insurmountable obstacles sometimes, especially when doing some unprecedented researches in those edge-cutting fields.
If there is still no feasible solution to conquer those obstacles even after we have maken great efforts and racked our brains, then how about consdiering resignation or turn to other possible ways?
Resignation is of two sorts, one rooted in despair, the other in unconquerable hope.
The man who has suffered such fundamental defeat that he has given up hope of serious achievements may learn the resignation of despair, and if he does, he will abandon all serious activities.
He may, camouflage his despair by religious phrases, or by the doctrine that contemplation is the true end of man.
But whatever disguise he may adopt to conceal his inward defeat, he will remain essentially useless and fundamentally unhappy.
The man whose resignation is base on unconquerable hope acts in quite a different way.
Hope which is to be unconquerable must be large and impersonal.
Whatever my personal activities, may be defeat by death, or by certain kinds of diseases.
And I may be overcomed by those difficulties, I may find that I have embarked upon an unwise course which cannot lead to success.
In a thousand ways the failure of purely personal hopes may be unavoidable, but if personal aims have been part of larger hopes for humanity, there is not the same utter defeat when failure comes.
There will be an answer. Let it be.
顺其自然吧，一切终会有答案。
From Beatles, "Let It Be"
There will be an answer, but it requires you to find out it.
Sometimes it may be unreachable, and the only thing we can do is to get closer and closer to the right one.
Don't easily cease from exploration, and be aware of not being distracted from things without use.