Quote 67
"I told the boy I was a strange old man," he said. "Now is when I must prove it." (3.76)
The old man is strange in his individuality, in his isolation from others; it is in solitude that he must prove his individuality, his unique and admirable nature.
Quote 68
If you’re not tired, fish," he said aloud, "you must be very strange."
He felt very tired now and he knew the night would come soon and he tried to think of other things. (3.83, 3.84)
The old man recognizes his own strange individuality in the fish.
Quote 69
An airplane passed overhead on its course to Miami and he watched its shadow scaring up the schools of flying fish…
[...]The boat moved ahead slowly and he watched the airplane until he could no longer see it.
It must be very strange in an airplane, he thought. I wonder what the sea looks like from that height? They should be able to see the fish well if they do not fly too high. (3.93-3.95)
In his isolation, the closest the old man gets to other people is a glance at a passing plane.