St. John was born at San Facondo in Spain and his youth was spent in a Benedictine monastery. Favoured by the Holy Ghost with a marvellous gift for peace-making (Collect), from childhood he exhorted other children to concord. During the civil war he preached peace in Salamanca and succeeded in putting an end to factions there.
He distributed his rich revenues among the poor (Epistle) and devoted his time to works of charity, to prayer and to the contemplation of divine wisdom (Introit).
In order to be ready when the Master came to fetch him (Gospel) he entered the Order of St. Augustine, where he was distinguished for his extraordinary devotion during Holy Mass. He died in 1470, crying out: "Lord, I place all my confidence in Thee at this last hour, and into Thy hands I commit my soul."
Let us ask the Holy Ghost, author of peace and source of divine charity, to fill us with the love and spirit of reconciliation of which St. John gave us the example, so that we may never be separated from Jesus (Collect).
Os justi meditabitur sapientiam, et lingua ejus loquetur judicium; lex Dei ejus in corde ipsius. * Noli aemulari in malignantibus: neque zelaveris facientes iniquitatem.
The mouth of the just shall meditate wisdom, and his tongue shall speak judgement: the law of his God is in his heart. * Be not emulous of evildoers: nor envy them that work iniquity.
(Psalm 36:30-31,1 from the Introit of Mass)
Deus, auctor pacis et amator caritatis, qui beatum Joannem Confessorem tuum mirifica dissidentes componendi gratia decorasti: ejus meritis et intercession concede; ut, in tua caritate firmati, nullis a te tentationibus separemur.
O God, the author of peace, and lover of charity, who didst adorn blessed John, Thy confessor, with a wonderful grace for reconciling those at variance; grant by his merits and intercession, that, being established in Thy charity, we may not by any temptations be separated from Thee.
From the Catholic Encyclopaedia: http://www.newadvent.org/cathen/08478a.htm