I'm trying to understand Manishearth's experiment in the answer here,
To try this out, close one eye. Now hold your arms straight out, nearly stretched, but not completely stretched. Now extend your index fingers (there should be about one inch between them). Now try touching them together. Try this a few times, then repeat with both eyes open. You'll realise how necessary the second eye is for judging depth.
I tried the experiment a few times but I am really not sure what I am supposed to see/ how the experiment works.
The one part I do understand is the reason they have said not to completely stretch the arms. If one does that, then by the sensation of arm being stretched will give a sense of depth, so it is necessary to not extend till to total arm length.
P.S: I completely understand the mathematics and fact we need two rays, but I think I am not getting the correct result for the experiment. Ideally an answer with pictures would be best.