(+) Woodstock took place when young people were interested in organizing for a cause. The "magic" was in the timing- war protests, political unrest, 2nd wave in the birth of real Rock N' Roll for the masses. Liberated attitudes about sex and love were developing, the birth control pill helped spark this. Vietnam War protests were going on all over the country and the subject matter of songs was significant and about a cause people wanted to stand up for. People questioned the "system", 40 years later people are still concerned. Many of the best and most popular bands gathered together on one stage, in one location. First large concert of it's kind.
(-) Some people just went for the party, and to get intoxicated.