"...on the cusp of something so profound, that it is hard to put it into words" means that something profound was about to happen at that point in time.
When we can even say for example, when Tom Brokaw was diagnosed with multiple myeloma in 2013, he was "on the cusp of something so profound, that it was hard to put it into words."
Explanation:
It could also mean when someone is about to enter a new experience either in professional life or otherwise. When somebody is overwhelmed by the current situation or position, it may be very difficult for the person to put into words the newly found position. In summary, "on the cusp of something" shows the intensity and profundity of the new situation.
‘The Last Lecture’, this book written by Randy Pausch will be read by generations to come.
It is a story of Randy Pausch himself who was a professor at an University in Pittsburgh.
In that university there’s a kind of tradition where professors of that University are told to give a lecture and assume it as if it is the Last lecture of their life. But for Randy, he didn’t even need to assume this, because it was certainly the Last lecture of his life because he was suffering from terminal cancer and he didn’t had much time left.
So in a way the organization purpose of Last lecture supported Pausch’s purpose for delivering the lecture, where he gave some of the best life adivces and words of wisdom from his life experience.
