A memo went out Thursday night An old speaker’s trick at the end introductory applause is to settle one’s hands on the sides of the podium to quiet an audience and signal time to begin speaking. When Sen. Elizabeth Warren of Massachusetts tried that on Thursday night, the cheers seemed for a moment as if they might subside. But Democratic National Convention delegates packed to the rafters in Chicago’s United Center were not having it. The cheers swelled anew, and louder still. Overcome with emotion, Warren pulled back from the podium a half step and wiped away a tear. Warren’s ovation was the loudest and longest of any speaker save for President Joe Biden’s hero’s welcome late Monday night, and Vice President Kamala Harris’s on Thursday as the Democrats’ presidential nominee. President Barack Obama’s matched Warren’s welcome in length but not in intensity. It was immediate and rapturous, as if springing from delegates’ hearts and souls. Joe Biden’s and Nancy Pelosi’s legacies will not be fully appreciated until historians weave together how their personal stories and battle scars, legislative accomplishments and deep political skills, built the country this generation’s children will inherit. Nevertheless, what we witnessed in Chicago was not only a generational passing of the Democratic Party’s torch from Biden to Harris, but the passing of an entire generation of Democratic establishment, though they may not yet know it. The term netroots gained traction in the early aughts as a label for progressive bloggers and activists who found each…