What does T.S. Eliot mean when he says,"Only those who risk going too far can possibly know how far one can go"

Put simply, only by "pushing the envelope" can you find
out what you are capable of. Eliot here is saying that only when humans test their
potential by "going too far" can they discover their truest abilities and possibilities.
In essence, this quote echoes the "carpe diem" (seize the day) sentiment found in other
great idioms and expressions from literature. Risk is inherent to gain, to put this
another way. "Nothing ventured, nothing gained," another saying says, and Eliot's quote
says the same thing more eloquently. Like other great poets, Eliot is encouraging
readers to test limits and boundaries.