It has often been said that songs happen in musicals when the feelings are too powerful for mere words, when music is required to express heightened emotion. This idea usually connotes feelings of great joy, such as in "I Got Rhythm" or great pain as in "My Man's Gone Now." Simply put into modern emoji terms, that's the happy face and the sad face, respectively. Of course, people are more complex and many other states of being make up the full gamut of human experience. Another state often requiring a song is the one perhaps best represented by the emoji with no mouth at all, that sensation of being stuck on a problem with no solution in sight.

Click through to read my selections for the Top Ten Showtunes About Angst.

10. "I'm Calm" from A Funny Thing Happened On The Way To The Forum

"I'm Calm" from A Funny Thing Happened On The Way To The Forum is a perfect illustration of how musical theatre can make magic out of angst. Hysterium, the befuddled slave in ancient Rome, may try to talk himself out of his anxiety attack, but the audience knows his attempt is in vain and delights at his futile efforts. One man's breakdown is, for everyone else, a showstopper.

9. "Green Finch And Linnet Bird" from Sweeney Todd

"Green Finch And Linnet Bird" from Sweeney Todd is not the type of song one may think of as being about angst, but leave it to Stephen Sondheim to imbue his work with multi-layered meaning. On the surface, Johanna is giving her pet a lovely serenade, but the ingenue's birdlike aria underscores the glaring metaphor of her own cagedness. What little comfort can be found in the song's final resolution, "If I cannot fly, let me sing," is quickly eradicated by the Judge breaking the bird's neck.

8. "Rent" from Rent

The title song from Rent opens the show with a bang. While the plot ultimately opens up to more complicated twists and loftier themes, the original question of "how we gonna pay rent?" resonates throughout as an increasingly profound dilemma, and one which is still topical today. Jonathan Larson's innovative use of rock sounds was extremely effective at communicating the drive of the East Village denizens' lives on the edge.

7. "I'm Not Getting Married Today" from Company

"I'm Not Getting Married Today" is another song by Stephen Sondheim which could be thought of as the epitome of the Broadway musical angst. The title lyrics reveal a bold statement belying Amy's confusion and doubts. Indeed, the verses do not merely proclaim her intention to break off the nuptuals, but rather bemoan her seeming inability to do so and its dreaded consequences.

6. "A Hymn to Him" from My Fair Lady

In My Fair Lady, Henry Higgins begins his relationship with Eliza Doolittle with great condescension and no tenderness. The intimacy and affection that eventually develops between them is a surprise to both. About halfway to that point, Higgins cries out in exasperated frustration with Eliza's quirks. He may not see his emotions for what they really are, but the audience understands what's going on quite clearly.

5. "A Puzzlement" from The King And I

In The King And I, prior to meeting Anna Leonowans, the King of Siam had enjoyed a somewhat simplistic, certainly predictable life. The introduction of his children's English governess into his court (and life) is a preview of the great changes coming around the world and throws the King into a tremendous quandary. Rodgers and Hammerstein's Shakespearean soliloquoy in song theatricalizes the moment memorably.

4. "The Nausea Before The Game" from In Trousers

Although In Trousers has never played Broadway (yet!), William Finn's importance as a contemporary Broadway songwriter and the fact that the show is a prequel to the Tony-winning Falsettos justify including "The Nausea Before The Game" on this list. Finn's other work has often explored similarly existential crises—and often brought to life with more theatrical dazzle — but rarely as acutely centered in the sturm and drang as in "The Nausea Before The Game."

3. "The B*tch of Living" from Spring Awakening

Speaking of existential crisis, the clear example from Broadway is the 2006 hit Spring Awakening. Duncan Sheik and Steven Sater's adaptation of the 1891 play by Frank Wedekind offered an anthem for the ennui of the somewhat disaffected millennial generation.

2. "The Right Girl" from Follies

Yet another Stephen Sondheim song to beautifully capture the hideousness of angst is "The Right Girl" from Follies. Judged by orchestrations alone, this number would top my list as its sound so expertly conveys the feelings of internal struggle and dissatisfaction. The song's more lyrical "B section" only serves to make the whole thing more heartbreaking.

1. "Finishing The Hat" from Sunday In The Park With George

Although Stephen Sondheim dismisses most suggestions of his work being at all autobiographical, he has allowed that Sunday In The Park With George is at least informed by his own experience as an artist, albeit one of a different discipline than George Seurat. This stands to reason as "Finishing The Hat" offer a shattering unparalleled look at the inner life of a creative.

(Ben Rimalower is the author and star of the critically acclaimed solo plays Patti Issues and Bad with Money, running in repertory through April 29 at The Duplex in NYC. Read Playbill's coverage of the show here. Visit him at benrimalower.com and follow @benrimalower on Twitter.)