Right, this is 100% correct.

Buy when there is despair and all hope is lose. Silkroad was shut down by FBI and btc went down to 70 USD, and after a few days, btc went up to 1200 USD.

Sell when everyone is buying and think bitcoin is the future. Example: when DELL accepts btc, btc went up from 500 USD to 680 USD, but several days ago, it went down.