Emerging from the letters of the Servant of God to his mother Elena Fiori is the question of zeal for the glory of God and of apostolate: “And you told me again that you entrusted this son of yours to Mary Help of Christians; well, he is precisely in her hands. I feel this predilection over me and every day I touch it first hand. I feel that it envelops me in a look of more than maternal tenderness. I feel that it personally guides everything for me and that is why I am always happy and calm, convinced that everything that happens around me, everything happens for my greater good. You should also believe this, mother... Besides, what is most important for the moment is that you help me to prepare myself worthily for this great step and you will do this by praying to our dear Help of Christians and to the Most Sacred Heart of Jesus so that they may pour torrents of graces upon this child of yours; and you will do this by praying to the Holy Spirit so that he may possess me entirely and raise me to the height of my sublime mission by communicating to me the fullness of his gifts. Dear mother, may this new consecration of your son to God, made in a more solemn and stronger form in the Sacrament of Holy Orders, make you proud, not before human beings but before God. It is a holy satisfaction that he grants you for all that you have suffered for His sake." (Letter of 19 May 1923)
As a new priest, Fr Costantino would receive the missionary crucifix in Valdocco, in the Basilica of Mary Help of Christians on 5 October and on 30 November he would leave for Assam, a mountainous area in the northeast of India, below Tibet, on the border with China, among the Khasi and Yaintia tribes. He would have the task of approaching the inhabitants of the area and in less than a year he would be appointed parish priest of the city.
Visiting villages, reaching the outskirts on rugged and tiring mountain paths, meeting families and children regardless of ethnicity and religion, starting with Salesian oratories to make Jesus and his Gospel known, was his mission, lived with the total gift of himself for the glory of God and the salvation of souls, until the end of his life on 30 January 1957 in Dibrugarh.
Not only the number of conversions and baptisms he administered, but also the fruit of his extraordinary mission, which continues to fill us with wonder, seems almost legendary. Prayer was the secret of his strength, love for the Sacred Heart of Jesus and Mary Help of Christians the inspiration for all his work.
What he wrote on his departure for India is significant: “I write under the gaze of the dear Help of Christians and of the Heart of Jesus to whom I entrust everything and from whom I hope everything, because they are my only inheritance and my great wealth. I was born in poverty, I grew up in poverty, but the love of Jesus led me to greater and more austere poverty of hand and heart, having renounced everything, perfectly everything, with a vow, by professing in the Pious Society of St Francis de Sales to be all for God, only for God."