1896-1900 He moved to Cagliari to study at the Regio Liceo Classico "Giovanni Maria Dettori". He was a bright student. He cultivated his passion for singing and he wrote some poems which were published in the local magazine «Il Pensiero» under the pseudonym of Sisto V. He was awarded with a diploma ad honorem in a dantesque contest where all the secondary schools of the Kingdom of Italy participated in. 

1901-1905 He studied literature at the University of Pisa, graduating with a thesis on Paolo Cortese e le origini della critica estetica letteraria [Paolo Cortese and the origins of the literary aesthetic criticism]. The president of the commission was Giovanni Pascoli, professor of Greek and Latin grammar. 

1906 In Rome he was appointed reader of the foreign press at Gabinetto Rava and he worked for the newspaper «Giornale d’Italia» together with Domenico Oliva. In the same year, he moved to Florence, where he worked at the philosophical library. He married Maria Pia Cabella, with whom he had six children.

1907 He wrote the first version of the libretto of his opera, then titled La Yura (Il giuramento ordalico). Cinque quadri di vita sarda in Gallura [La Yura (The ordeal oath). An opera in five acts of Sardinian life in Gallura].
 
1908 He edited the book Ragguagli di Parnaso [News-sheet from Parnassus] by Traiano Boccalini, published two years later by Rocco Carabba as part of the series Scrittori nostri [Our writers] edited by Giovanni Papini. It is thought that in this period, he made first contacts with the intellectuals linked to the Florentine magazine «La Voce» and performed his first concerts in which he introduced and reinterpreted traditional Sardinian repertoire. 

1909 In Florence he worked for the Italian literary magazine «La Voce» and he made friends with its founder, Giuseppe Prezzolini, as well as with Giannotto Bastianelli and Ildebrando Pizzetti. He wrote some articles about the vindication of the rights of the island under the pseudonym A.B. Salu [a play on words based on the term "abbisalu" which in Gallurese dialect means "guess it"].

1911 One of his lecture-concerts was reviewed favorably in the newspaper «The Westminster Gazette», which described his way of singing "spontaneous and very charming". During the following years in Italy, he proposed the lectures that he had held in London, always enriching them with new insights. When he returned to Italy, he published an essay entitled Un poeta di Gallura (Franciscu Multineddu) [A poet from Gallura – Franciscu Multineddu] in the newspaper «La Nazione». 

1911-1916 He moved to Romagnano Sesia [near Novara] where he taught literature at the Scuola Tecnica-Collegio "Curioni". He became its headmaster and he founded a liberal arts library and a monthly news-sheet (La Bibliotechina), in which students published articles about local ethnography, among the others. 

1913-1914 He continued to hold his lecture-concerts in several locations all over the Italian territory. On February 1st, in Turin, at teacher Ferraria's ballet school, they played the score of La Jura for voice and piano, before composer Leone Sinigaglia and sculptor Leonardo Bistolfi; Gabriel himself sang the vocal parts, accompanied with the piano by Maestro Perracchio.

1916-1919 He was enlisted as an infantry officer in the Brigata Como and in the Compagnia X, and he published the illustrated manual Il respiratore inglese e i gas in guerra [The English breather and gases in war] for trainers.

1919-1920 He entered politics. He was one of the founders of the Tempio branch of the Associazione Nazionale Combattenti [ANC] and he became a member of its Central Committee but he was not elected at the general elections. Instead he won the local government elections held the following year and therefore he became a district councilor.

1921 He ran for the general elections as a candidate of the Partito Sardo d'Azione, but he was not elected. He kept on performing his lecture-concerts upon request of the Royal Family at Villa Savoia and at Villa Margherita. He presented the a tàsgia choir of Aggius at the Teatro Quirino in Rome and the performance became a news item; the event was attended also by Prezzolini, Eleonora Duse and Grazia Deledda. This was the first of a new series of lecture-concerts where typical Sardinian multipart singing was sung live by its performers. 
He had an extensive exchange of letters with D'Annunzio, who hosted him many times at his villa in Cargnacco on Lake Garda. Together they drafted a project for a "regional opera house" and a book about Italian songs. He met minister Giovanni Gentile thanks to the mediation of Prezzolini, and started to work on a syllabus for teaching music in schools which implied the use of the phonograph. He also prepared a project for setting up a National Ethnic Record Library; the initiative did not come to life because of lack of funding, even though the project was approved by the Council of Fine Arts.

1925 He founded the music magazine «Il Suono» published by Phonos of Giovanni Treccani, which was short-lived. He continued to hold his educational lectures in several Italian cities.

1926 He was the first one to record Benito Mussolini's voice on a wax cylinder at Palazzo Chigi. He dealt with sound cinema, cooperating in the design of the sound film synchronizer Fonofilm Italico, Robimarga patent. He also prepared some samples of sound films: Tarantella by Rossini and Il Cigno [The Swan] by Saint Saëns, successfully presented in Padua and in London.

1927 He collaborated with Giovacchino Forzano in the drafting of the libretto of Il Re [The King], the last opera by Umberto Giordano staged one year later at the Teatro alla Scala in Milan, directed by Arturo Toscanini. He published the first printed version of the libretto of the opera La Jura. Cinque quadri di vita gallurese [The Oath. An opera in five acts of life in Gallura], with valuable illustrations by Melkiorre Melis.

1928 La Jura debuted at the Politeama Regina Margherita in Cagliari with five performances [April 21-28]. The cast featured the soprano Carmen Melis as the protagonist. The magazine «Fontana Viva» in Cagliari, founded by Raffa Garzia, dedicated a special issue to this.

1929-1932 Upon Umberto Giordano's request, he wrote verses of the aria È l’april che torna a me [It is April coming back to me] and for the Inno del Decennale [Anthem of the tenth anniversary], which Mussolini commissioned to Giordano. He edited the historical catalogue for the record company Edison Bell. 
In Rome, he contributed in the founding of the Discoteca di Stato [State record library] «in order to collect and to preserve for future generations, live voice of those Italians who have made the country illustrious and have rendered outstanding services in any field», of which he became director in 1932. Two years later, the Discoteca di Stato [today Istituto Centrale per i Beni Sonori e Audiovisivi – Central Institute for the sound and audiovisual heritage] became by law, the authority for preserving all sound material produced in Italy. In 1932, he made a series of four short documentaries entitled Visioni di Sardegna [Visions of Sardinia] for the film studio Cines-Pittaluga. 

1932-1934 For the register of the Discoteca di Stato, he recorded the voices of the Duke of the sea Paolo Emilio Thaon di Revel, of Pietro Badoglio, Cesare Maria de Vecchi, Italo Balbo, Edward De Bono, Guglielmo Marconi, Luigi Pirandello, Grazia Deledda and Giovanni Gentile. 
He prepared a series of five double records including some monodic songs played with a guitar [sang by Gabriel himself] and the polyphony of the a tàsgia singing of Aggius for the Fono Roma editions. The same record company published a record with his interview to tenor Giacomo Lauri-Volpi. He edited the phonographic record of the Italian Condottieri, of which he edited the radio-broadcast on November 4th, 1933. 
He participated as a speaker at the Third National Conference on popular arts and traditions with a speech on carelessness in sound recording, highlighting the need to follow strict procedures in order not to distort sound documents. His intervention was published under the title «Laofonografia» [Laophonography], in which he also criticized the lack of funds for the Discoteca di Stato. He published a collection of his educational lectures entitled Musica a centimetri [Music in centimeters], with a preface by Giovanni Gentile. 

1935 He worked as assistant director of the film Casta Diva for the celebrations of Bellini's centenary, directed by Carmine Gallone. He participated as speaker in the conference on film sound tracks organized within the festival Maggio Musicale Fiorentino. He made the documentary Nei paesi dell’orbace [In the villages of orbace – Sardinian typical wool cloth], published the following year by the film company Cines-Pittaluga. 

1936-1938 He traveled in the new and the old Eritrea to collect the items for an Exhibition on the production activities of Eritrea, organized at the Fiera di Levante in Bari and in Tripoli. He was in charge of arranging and directing the local government library.

1940 As the Head of Research Section of the government administration, he organized a radio listening network for all Eritrea. He cooperated in the collection of items for the Exhibition on the Italian Territories Oversea.

1941 When the Italian colony became a British colony, he remained the Head of Research Section and he was appointed consultant and translator of the legal acts section of the British Administration of Eritrea. He wrote the unpublished book 160 proverbi eritrei [160 Eritrea proverbs] and Profili eritrei [Eritrea profiles], a collection of the articles on the indigenous ethnography published over the four previous years.

1949 He was sent to New York to provide historical and legal assistance to the mission entrusted to plead the cause of the independence of Eritrea at the United Nations. In New York he met Giovanni Prezzolini, his longtime friend and emeritus professor of Italian studies at Columbia University.

1950 He was appointed chairman of the Associazione Stampa Eritrea, and he organized lectures and shows in which some of his works were performed: string quartets, sonatas for piano and romances for voice and piano. He was appointed honorary Chairman of the Istituto Radiotecnico "G. Marconi" and of the Circolo Universitario Asmarino.

1951 He claimed the Archivio Storico Eritreo [Eritra historical archive] for Italy and brought to Rome 7.2 tons in documents relating to the years 1880-1940. He held a short series of lectures in Sardinia and Rome on: "Eritrea, an Italian invention".

1952 He edited the series Composizioni per pianoforte [Compositions for piano] and Trittico per pianoforte [Triptych for piano] published by the association "Amici del libro". He returned to Asmara to take care of the Library, entrusted to the Italian administration by the Paris peace accords.

1953 He returned to Italy and he lived in Rome. In that period he made the documentary Etnofonia della Sardegna [Ethnophonology in Sardinia], in partnership with Remo Branca, commissioned by the Ministry of Education [Cineteca scolastica].

1954 The Ministry of Education entrusted him to edit a series of ethnographic books, and the first published was his Voci e canne d’armonia in Sardegna [Harmony voices and pipes in Sardinia]. 

1955 During the "Sardinian week" festival in Milan, one of his String Quartets was performed.

1956 He presented the project for a Sardinian Ethnographic record and film library at the National Conference on Popular Traditions in Cagliari, project commissioned three years earlier by the Tourism Department of the Sardinian regional government. 

1957-1958 Ennio Porrino, headmaster of Cagliari's school of music, asked him to prepare a syllabus for a course of Sardinian ethnophonics. Despite his advanced age, Gabriel began to teach the courses in February 1958, but he stopped teaching the following year due to the untimely death of Porrino. 

1959 The President of the Italian Republic awarded him with a gold medal for culture. La Jura was staged at the Teatro Massimo of Cagliari [May 21-22].

1960 He composed the background music for the documentaries Le torri segrete [The secret towers] and Il re dell’isola [The king of the island] by Remo Branca.

1961 He published Cardi sardi [Sardinian thistles], a collection of his articles published in the newspaper, «Giornale d’Italia».

1962 The Ministry of Culture asked him to prepare a Course of music education – records included – for the new established unified secondary schools. The following year, he completed it with a short book on music history.

1964-1967 He continued his work as a freelance journalist and essayist, and also founded and directed the monthly magazine «La Scelta».

1971 He published the book La Sardegna di sempre [The usual Sardinia], with a preface by Giuseppe Prezzolini and illustrated by Dino Fantini.

1976 He edited the appendix entitled Canto e poesia [Singing and poetry], in the book by Giulio Cossu dedicated to the Poesia dialettale in Gallura 1900-1800-1700 [Dialect poetry in Gallura 1900-1800-1700], in which he included several transcriptions of traditional Sardinian pieces of music. 

1980 He died in Rome on November 28th, aged 99.