'Hoc signum erit in coelo.' On the Iconographical Programme of the Church of the Knights of the Cross with the Red Star by Charles Bridge in Prague
The programme of the St Francis Church in Prague, created from the 1680s to the third decade of the 18th century, reflects the piety of the Knights of the Cross with the Red Star, which in the late 17th century were a knightly order that propagated the veneration of the Holy Cross and the legend about their Palestinian roots and their former military mission. The new church was laid out in the shape of a Greek cross - which was difficult to build in the corner of the cloister complex. Its façade was decorated with symbols of the Sacrifice and the Cross of Jesus (e.g. Samson's jawbone of an ass, winged lightening) and its interior was clad in red marble symbolising the Holy Blood of Christ. The Cross serves as a leitmotif of the High Altarpiece and of the side altar's 'Finding of the Cross' accompanied by the coffin of two early Christian Roman martyrs venerated by the order as holy knights. The 'Sign of the Son of Man' is a central motif of the 'Last Judgement', depicted in the church's dome and enriched with a depiction of the holy knights gathered around Constantine the Great and St Helene and with an inscription that reads Hoc signum erit in coelo. Similarly, the depictions of four Evangelists in the pendentives are enriched with chrystological motives (the Cross, the flag of the Resurrection, the priest's vestments). The programme of the Church of St Francis, based on the works of the Church writers and on the breviary prayers assigned for the feasts of the Finding and Exaltation of the Cross, advances the idea of Jesus' triumph over death and material destruction, his dignity as the archpriest, and the redemptive power of his Holy Blood.