Why did fdr sign the social security act in 1935 as a part of the second new deal?

Franklin D. Roosevelt signed the Social Security Act of 1935 as a part of the second New Deal to end and contain the Great Depression. It also a new solution for the problem of the old-age people and those who already retire. It also helped alleviate the Government of some spending because the insurance was from the contribution from the payroll and taxes of the employees and individual's wages.