Charles Parker Jr. (August 29, 1920 - March 12, 1955), also known as Yardbird and Bird, was an American jazz saxophonist and composer. Parker was a highly influential jazz soloist and a leading figure in the development of bebop, a form of jazz characterized by fast tempos, virtuosic technique and advanced harmonies. Parker was a blazingly fast virtuoso, and he introduced revolutionary harmonic ideas including rapid passing chords, new variants of altered chords, and chord substitutions. His tone ranged from clean and penetrating to sweet and somber.

Parker's life was riddled with depression and heroin addiction. This addiction caused him to miss performances and be considered unemployable. He frequently resorted to busking, receiving loans from fellow musicians and admirers, and pawning his saxophones for drug money. Heroin use was rampant in the jazz scene, and users could acquire it with little difficulty.  Although he produced many brilliant recordings during this period, Parker's behavior became increasingly erratic. Heroin was difficult to obtain once he moved to California, where the drug was less abundant, so he used alcohol as a substitute. A recording for the Dial label from July 29, 1946, provides evidence of his condition. Before this session, Parker drank a quart of whiskey. According to the liner notes of Charlie Parker on Dial Volume 1, Parker missed most of the first two bars of his first chorus on the track, "Max Making Wax". When he finally did come in, he swayed wildly and once spun all the way around, away from his microphone. On the next tune, "Lover Man", producer Ross Russell physically supported Parker. On "Bebop" (the final track Parker recorded that evening) he begins a solo with a solid first eight bars; on his second eight bars, however, he begins to struggle, and a desperate Howard McGhee, the trumpeter on this session, shouts, "Blow!" at him. Charles Mingus considered this version of "Lover Man" to be among Parker's greatest recordings, despite its flaws. Nevertheless, Parker hated the recording and never forgave Ross Russell for releasing it. He re-recorded the tune in 1951 for Verve.  Parker's life took a turn for the worst when his 2 year old daughter tragically passed away from pneumonia. He attempted suicide twice in 1954, which landed him in a mental hospital.  When Parker received his discharge from the hospital, he was clean and healthy. Before leaving California, he recorded "Relaxin' at Camarillo" in reference to his hospital stay. He returned to New York, resumed his addiction to heroin and recorded dozens of sides for the Savoy and Dial labels, which remain some of the high points of his recorded output. Many of these were with his so-called "classic quintet" including Davis and Roach. Answer this question using a quote from the following article:

why was he depressed?
Parker's life took a turn for the worst when his 2 year old daughter tragically passed away from pneumonia.