Leonard Bernstein is an iconic figure in the history of music.

As a composer, conductor, author, and lecturer, he was a person who influenced so many people’s lives, especially with his Young People’s Concerts with the New York Philharmonic.

Bernstein (1918 - 1990) would have been 100 in August. Orchestras all over the world are celebrating his centennial.

Leonard Bernstein was a trail-blazer, and without him and his influence, I am not sure if I would be standing on a conductor’s podium today.

Before Lenny (as his friends called him), symphony orchestra conductors were older European males. There were no American-born conductors working with any of the orchestras in the United States.

Imagine everyone’s surprise when the 26-year-old, American-born Leonard Bernstein, Assistant Conductor for the New York Philharmonic, stepped in for the ailing Bruno Walter. It was an historical moment that changed the landscape of the conducting field forever.

Bernstein was not just a conductor. He was also a composer and later in his life an author and educator.

Bernstein was 39-years-old when he wrote what is perhaps his most famous composition, the music for the hit 1957 Broadway musical, “West Side Story,” with lyrics by Stephen Sondheim, book by Arthur Laurents, and based on “Romeo and Juliet” by William Shakespeare.

As I was programming the music for the Allentown Symphony Orchestra’s 7:30 p.m. April 14 and 3 p.m. April 15 concerts at Miller Symphony Hall, Allentown, I knew that this was a piece that had to be included.

But I didn’t want to just perform pieces by Leonard Bernstein in the concerts, so I also included American composers who influenced his work. The two that came immediately to mind were Aaron Copland, and George Gershwin.

Copland (1900 - 1990) and Gershwin (1898 - 1937) are quintessential American composers who defined a new sound and style of music in the early half of the 20th century. Even today, they are the epitome of American classical music.

We open the ASO concerts with Copland’s famous “Fanfare for the Common Man,” written in 1942 for the Cincinnati Symphony in an effort to arouse patriotic sentiment after the beginning of World War II. I like the title, although if used in reference to Leonard Bernstein, he is anything but common.

Next on the concerts’ program is George Gershwin’s trail-breaking 1935 opera, “Porgy and Bess.”

Never before in American history had an opera of this type been written. Gershwin, who was thought of more as a Broadway show composer, or jazz composer, surprised the critics with this unique setting of life in Charleston, South Carolina, in the 1920s.

Featured soloists for “Porgy and Bess” are some of the finest singers in the country. Baritone Lester Lynch has performed major roles with the San Francisco Opera, Spoleto Music Festival, Berlin Philharmonic, and more. He’s regarded as the leading person in the nation to sing the role of Porgy.

Soprano Laquita Mitchell, singing the role of Bess, is equally talented and has performed with the Boston Symphony, San Francisco Opera, Los Angeles Opera, and many more. What a pair they will make as they sing together with the Allentown Symphony.

For the role of Sportin’ Life, we will showcase Jermaine Smith, who has brought this character to life on so many stages throughout the United States.

This stellar cast will be joined by the Allentown Symphony Chorus in a concert performance of selections from “Porgy and Bess” not to be missed.

For the second half of the program, after the “West Side Story Symphonic Suite,” we will conclude with a little-known piece by Bernstein, his “Olympic Hymn,” written for the 1980 Olympics in Germany. Joining the ASO for this piece will be the El Sistema Lehigh Valley Fellowship Choir with director Kyle Keller, Lehigh Valley Charter High School for the Arts Choir, with director Neil Chaban, and the Hackensack, N.J., High School Advanced Chorus, with director Julie Platte.

The triumphant “Olympic Hymn” brings together the Allentown Symphony, Symphony Chorus, guest choruses, and soloists in a spectacular conclusion to an epic concert in celebration of Leonard Bernstein’s 100th anniversary.

“Meet the Artist” with Allentown Symphony Music Director-Conductor Diane Wittry, Allentown Symphony Chorus Director Eduardo Azzati and conducting fellow Bobby Collins, noon-1 p.m. April 13, Miller Symphony Hall, Allentown. The talk is free and open to the public.

Diane Wittry is Music Director and Conductor of the Allentown Symphony Orchestra, Artistic Director of the Ridgewood Symphony, N.J., and author, “Beyond the Baton” and “Baton Basics” (both, Oxford University Press).

Tickets: Miller Symphony Hall Box Office, 23 N. Sixth St., Allentown; allentownsymphony.org; 610-432-6715. Free student tickets are available for Allentown Symphony Orchestra concerts.