Who do some people post things that they did not write and do not give credit to the original source? So ... maybe you don't know who the original source is. Maybe you got it in an email that has forwarded and then forwarded a zillion times. But why post it as if it were your own words??
It really irks me! It this were a class, you would be accused of plagiarism and receive an F!
A word to the wise everyone ... next time someone posts something that is seemingly enlightening or brilliant, copy a string of it and Google it! Sorry to say, you will probably be disappointed.