Short idea (16): Everything you experience is real, but not everything is real in the same way: Some things are useful and substantial and important to you; others are dangerous; others are pale reflections, elusive and amorphous and hard to describe and maybe fleeting and unrepeatable and useless; others mislead you like a delusion that comes into the head while lying in bed on a long Winter's night.
Short idea (50): If you think nobody in the world cares about you, you have to be willing to look closely at the possibility that you don't care about anybody in the world. There is also the possibility that you are absorbed in a waking nightmare (in which nobody cares about you) and that you're not aware it's just a nightmare.
Short idea (103): A house can make sounds like those of a living creature. Some people, especially at night mistake these sounds for the sounds of living creatures entering their houses.
Short idea (124): Even old wise men can have delusions, even many delusions.
Errors, Illusions, Hallucinations, Delusions:
A simple error or a mistake isn't always an illusion or hallucination or delusion. You can be tired and adding a series of numbers and make a mistake. Or you can hear it will rain today and believe it and be wrong.
The Error of George Berkeley's Tree in the Park Argument
The so-called Tree in the Park Argument or Master Argument of the Irish philosopher, Bishop George Berkeley (1685-1753), has been analyzed and rejected by most philosophers, but it remains intriguing to many lay people. The following is Berkeley's presentation of the argument from his 1710 book, A Treatise Concerning the Principles of Human Knowledge. The conclusion of the argument is that there are no material substances, that is substances "existing unthought of or without the mind," and the argument is trying to prove that we can't even conceive of such things existing independent of mind. It is worthwhile for us who are studying things from a psychological angle to show the fallacy of his argument in a way that helps us remember the differences between imagination and perception and between the real and the unreal (and the ideal).