President Obama and three former presidents: Jimmy Carter, Bill Clinton and George W. Bush attended a summit in Austin celebrating the 50th anniversary of the Lyndon B. Johnson's Civil Rights Act.

"What President Johnson understood is that equality required more than the absence of oppression. It required the presence of economic opportunity," President Obama said when giving his keynote address at the summit Thursday.

President Obama compared Johnson's presidency to the current political and economic climate.

"Today we remain locked in this same great debate about equality and opportunity and the role of government in assuring each. There are some who argue nothing has changed,  that racism is so embedded in our DNA,that there's no use in playing politics... but such theories ignore history."

President Obama rejected such cynicism and had strong hopes for the nation. He praised President Johnson's stand for equality and civil rights.

Watch the speech:

Former presidents George W. Bush, Jimmy Carter and Bill Clinton also gave speeches in honor of LBJ and the Civil Rights movement. Although President Johnson has been criticized for his involvement with the Vietnam War, he is being remembered for landmark  legislation that included the Civil Rights Act of 1964 and the Voting Rights Act of 1965.