Imagine a circle that contains all of human knowledge:
By the time you finish elementary school, you know a little:
By the time you finish high school, you know a bit more:
With a bachelor's degree, you gain a specialty:
A master's degree deepens that specialty:
Reading research papers takes you to the edge of human knowledge:
Once you're at the boundary, you focus:
You push at the boundary for a few years:
Until one day, the boundary gives way:
And, that dent you've made is called a Ph.D.:
Of course, the world looks different to you now:
So, don't forget the bigger picture:
Keep pushing.