When the Kentucky Derby goes off this afternoon, we will be thinking of what happened exactly 50 years ago at the 99th Run for the Roses. That’s when the Derby record was shattered by a three-year-old demi-god (maybe not so demi, some would say) named Secretariat who would go on to break the record in the Preakness and, again, in the Belmont, to emerge as the greatest multicellular being of all time.