There sure was a lot of Purple on the Plaza on Tommie Tuesday, and for good reason.

More than 1,500 students, faculty and staff gathered in the lower quadrangle and on John P. Monahan Plaza over the noon hour to pay tribute to Father Dennis Dease, who will retire June 30 after 22 years as president of St. Thomas.

Students planned the festivities and played off St. Thomas traditions established during his tenure, including a March Through the Arches and a clapping crowd that lined sidewalks in purple t-shirts with “Father Dease’s Farewell Crew” printed on the front and “Thanks Father Dease” on the back.

Dease walked with outgoing Undergraduate Student Government President Mike Orth and Hana member Jessica Algoo from the Arches to Monahan Plaza, trailed by international students carrying flags from more than 20 countries.

Orth welcomed the crowd and thanked Dease for his lifetime of service to the university and, in particular, to its students by listening to them and making them feel engaged, respected and appreciated.

“I have learned so much from this incredible man,” Orth said. “Never have I met someone who better defines the role of a humble, quiet servant-leader who genuinely cares about the well being of his community. He is a man who commands the attention of a room but quickly turns that attention around into a voice of tenderness and care.

“As I wrapped up my very last meeting with him in April, I thought to myself, ‘This is the leader I hope to become some day.’ ”

Dease called the turnout “a wonderful gesture” and said it underscored his pride in St. Thomas students.

“I have long believed that the ultimate measure of the quality of a university is the quality of its graduates – and ours are extraordinary,” he said. “I can say the same thing today about the quality of our students, who are outstanding in every sense of the word.”

Dease said he always has been guided and motivated by two goals as president: to continually improve the quality of a St. Thomas education and “to make sure we live up to – and live out – our mission statement to educate students ‘to be morally responsible leaders who think critically, act wisely and work skillfully to advance the common good.’ ”

The Festival Choir sang “Thanks,” which it also performed at the Opening Doors capital campaign closing dinner last October, and the president received two gifts.

International students gave him a huge postcard with a map of the globe surrounded by their signatures, and Algoo announced that a blue beech tree will be planted on the east side of the quadrangle in his honor. A plaque under the tree will read:

“This tree is dedicated to the Reverend Dennis Dease in gratitude and celebration of his extraordinary commitment, leadership and devotion to undergraduate students during his 22 years of president of the University of St. Thomas. April 30, 2013.”

Algoo then quoted a Greek proverb on a wall in the Anderson Student Center: “A society grows great when people plant trees in whose shade they know they shall never sit.” Dease later returned to the microphone for final words:

“I don’t know about you,” he said, “but I fully intend to sit under that tree.”