"The Panic of Growing Older" highlights the different stages in man's life. The persona refers to the ageing process as inevitable and bound by time. The fear of ageing dominates man's psyche through all the stages of life. Our ageing is manifested in our progressive loss of physical strength and our susceptibility to illness, some of which defy diagnoses.
After age thirty, there seems tp be nothing left of hope. References to "legs cribbed", "no sudden leaps", "copybook bisected" suggest this interpretation. Only "failure" stares us in the face as we realize that the things we used to do, we can no longer do, in spite of science offering hope of longer life. Disillusionment now sets in: "Inner satisfaction dwindles in sharp blades of expectation". In the end we resign ourselves to a passive rather than an active life. This finality is captured in the line, "From now on the world has you".
Points to note:
(a) The inevitability of ageing.
(b) The ageing process, beginning with childhood 'fluttering nwings" and ending in death.
(c) Our initial hopes and expectations as we grow and the panic of aborted dreams, followed by terminal illness.
(d) Our succumbling to fate/death.