He studied at the Brera Academy in the 1930s, where he was taught by renowned artists, including painters Aldo Carpi and Pompeo Borra, and sculptors Francesco Messina and Marino Marini.
Humility features in many of his works, including the depiction of characters such as beggars, vagrants, and vagabonds, and themes such as loneliness, abandonment, exile, pilgrimage, and poverty.
His oil paintings have been described as dense and oily like those of Paul Cézanne, and his style has similarities to the fantasy settings of Marc Chagall and "pictorial culture" of Egon Schiele.
His growing stature as a painter in Italy led to exhibitions at increasingly prestigious events, such as the Venice Biennale and Rome Quadriennale.
It ultimately led to Longaretti earning the "Chair of Painting" and becoming the director of the Accademia Carrara in Bergamo in 1953, a position he held until he retired from it in 1978.
[11][12][13] He studied there until receiving his degree in 1939,[14] during which time he was classmates with Arnaldo Badoli, Aldo Bergolli, Bruno Cassinari, Edmondo Dobrzanski, Ibrahim Kodra, Ennio Morlotti, and Italo Valenti.
[1][11] Some of his favourite professors included Carpi, sculptors Francesco Messina and Marino Marini, and painters Pompeo Borra and Mauro Reggiani.
[11] It was at this time that Afro, Badoli, Bergolli, Renato Birolli, Carpi, Cassinari, Cherchi, Alfredo Chighine, Grosso, Renato Guttuso, Dino Lanaro, Giuseppe Migneco, Mantica, Morlotti, Aligi Sassu, Ernesto Treccani, Valenti, and Emilio Vedova (and later Giuseppe Ajmone and Kodra) established a movement against the Novecento Italiano ("l'antinovecentismo") to pursue opportunities offered by Cubism, a movement they named Corrente.
[18] Years later, Morlotti stated that the two friendships he valued most were those with Romano Trojani and Longaretti, the latter with whom he had spent much time discussing the river Adda passing through their hometown.
[13] In the famous 15 December 1939 editorial in the movement's magazine Corrente, the group reiterated its anti-fascist commitment in opposition to the National Fascist Party headed by Benito Mussolini by promoting an artist project about "all aspects of the reality in which we live in our time in history", which Longaretti fully embraced by portraying themes of humility.
[1] He continued to paint during his service, even when on the front lines, committing to canvas images of "dramatic testimonials" considered prohibited, such as Albanian villages razed by Italian troops.
[26] He maintained an "elegant studio" in the Città alta of Bergamo,[7] which was jam-packed with paintings and books,[27] and three in Corniglia,[26] a frazione in the comune of Vernazza within Cinque Terre.
[28] He considered it his adoptive home and returned there to paint when he needed tranquility, spending holidays and about four months a year there, as there was little tourism there to distract him.
[29] In 2009, he was among the 500 artists in all fields (including painting, sculpture, cinema, theatre, dance, music, photography, and architecture) to receive an invitation from Gianfranco Ravasi, a cardinal and president of the Pontifical Council for Culture, to meet Pope Benedict XVI.
[32] Longaretti stated that he preferred creating works that are "accessible and immediately enjoyable" by the public,[30] and considered himself as "isolated in the panorama of Italian art".
[21][34] In an exhibition catalogue for the Pinacoteca civica di Follonica starting October 2007, curator Paola Artoni stated that Longaretti's "pictorial culture" has striking parallels to the works of Egon Schiele and even Vincent van Gogh.
[34] Common themes in his art are beggars and vagrants, which he uses as a symbol for human frailty, and mothers opposing violence, characters that could be mistaken for the Madonna.
[21] They are the "representation of taciturn labours and sufferings of existence" in search of a more dignified fate,[34] and are often depicted in enchanted or fantasy settings conceptually similar to the style of Marc Chagall,[34] a comparison with which Longaretti agreed.
[11] His works have been exhibited worldwide, including at London, New York City, Paris, Buenos Aires, Toronto, Ottawa, Amsterdam, Monaco, and Stockholm.
[38] On this occasion the card sent by the United Nations then High Commissioner for Human Rights, Dame Mary Robinson, to all Heads of States in the world, for the year 2000 greetings, used the reproduction of a Mother and Child painting by Longaretti.
[40][41] On the night of 27 March 1999, the painting and seven other works were stolen from the church by a Neopolitan man, who later sold them to an antique dealer from Abruzzo who was unaware of the theft.
[42] It consists of 14 mosaics framed within modern aedicula, designed by Longaretti in 1971 and realized by the Milan tile company Peresson, replacing the deteriorated artwork of Giovanni Brighenti.
[51] In 2007, five students who were the first graduates from the economics program at the University of Bergamo satellite campus in Treviglio received the Cartèla del Campanil (in Bergamasque dialect), a numbered print of a Longaretti work from the comune of Trevilgio, in addition to their diploma.
[4] In a 2013 interview with "Amici di Gabry" he stated that despite residing in Bergamo, he remains "trevigliese" (from Treviglio) as that is where his roots, family, and culture developed.