In 1933, a friend, Bruno Rossi, who had obtained a chair in physics at University of Padua, invited him to finish his studies there, which he managed to do, taking his degree magna cum laude.

[1] Curiel was, however, subject to neurasthenia, and for some time was attracted to the anthroposophy of Rudolf Steiner, whose system of thought and practical life appeared to offer, as he confided to Rossi in a letter, a stimulus towards self-discipline that might allow him to adjust his physical and psychological outlook to the intellectual and moral rigour he already displayed.

[2] The Communist party tried to infiltrate union and student organisations run by the fascists in order to subtly reorient them towards an attitude critical of Fascism.

To this period may be dated an article he wrote under the pseudonym of Giorgio Intelvi, entitled Our economic and union work with the masses and the struggle for democracy, which appeared in the review The Workers' State.

[3] Curiel maintained that it was necessary to pressure students, by means of university publications, to get them to abandon the still residually corporative ideology of 'left-wing fascism', and have them recognize the 'class struggle'.

The period was one that declared a turnaround in the regime's politics, which now embraced a naziphile position, In November of the same year laws for 'the defence of the (Italian) race were decreed, and, in consequence, Curiel, like so many others, was deprived of his rights to teach.

Eugenio Albo, who oversaw the newspaper 'The Voice of Italians' (La Voce degli Italiani) in fact would later be exposed as a spy of the OVRA.

Even though no specific charges were laid against him – indeed, he was even considered as a potential editor for a newspaper that was to be published in Alexandria (the idea did not bear fruit) – Curiel passed months of great bitterness in Paris, an experience that led him, in January 1939, to take up contacts with other exponents of antifascism abroad, both socialists and members of the Justice and Liberty (Giustizia e Libertà) movement.

In April he returned once more to Switzerland, where he discussed matters with Pietro Nenni, who was well-disposed to the idea of an accord with communists, and the possibility of organizing groups in Milan to pursue concerted action.

In Italy, in articles and letters, he continued to press for the necessity of establishing 'bonds' (with the communists' that would 'enlarge our contacts with the masses and exercise some influence on the bureaucratic tendencies of the PCI and its blind, passive discipline'.

Several hundred detainees, mostly communists, were expedited to the island, among them Luigi Longo, Giovanni Roveda, Walter Audisio, Pietro Secchia, Umberto Terracini, Camilla Ravera, and Giuseppe Di Vittorio.

Among the socialists and the actionist militants are to be counted figures like Sandro Pertini, Altiero Spinelli, Ernesto Rossi, Riccardo Bauer and Curiel's friend Eugenio Colorni, who had been arrested in September, 1938.