In his book Knjiga o Istri (A Book about Istria), published posthumously, he argues for a common national identity of Croatian and Italian lower class' people autochthonous of Istria, the Istrian man being "a kind of local patriot, isolated in his intimacy from both Italy and Yugoslavia."

As an excellent teacher, he was selected to study and moved to Zagreb, where he graduated at the Higher Pedagogical School and Faculty of Philosophy.

The introduction of this subject provoked criticism from scientific and political circles, but he made considerable efforts to prove that his initiative was valuable.

In the journal Pedagoški rad (Pedagogical paper), 1964, explaining the justification and importance of the "Teaching of the Homeland", he summed up what he deemed the determinants of the Istrian mental being: according to Peruško, the Istrian man remained somewhat in his intimacy somewhere on the border of the Slavic and Latin world, between the Balkans and the Apennines; "he is in fact a kind of local patriot, isolated in his intimacy from both Italy and Yugoslavia.

The political task of Teaching in the homeland was breaking "that feeling of isolation and removing the feeling of national inferiority," helping that 'man at the crossroads' with knowledge that will become a conviction,[1][2] best expressed in Peruško's Knjiga o Istri (A Book about Istria), published posthumously by Školska knjiga in 1968, as a co-authored work (Miroslav Bertoša, Josip Bratulić, Zvane Črnja, and others).