Making my way through Grand Central’s Vanderbilt Hall, I was stopped by these super-sized graphic affirmations. In celebration of Nelson Mandela’s 91st birthday July 18, this installation documenting Mandela’s historic humanitarian achievements will be shown through July 22nd. Designed by Ralph Appelbaum Associates, the exhibit features six illuminated 3-D action words: act, listen, lead, unite, learn and speak, highlighting Nelson Mandela’s lifelong struggle against apartheid and other social injustice, and aiming to motivate our own potential for positive social change. Especially powerful are the personal messages the public is encouraged to share.