This is the most powerful show London's National Gallery is ever likely to hold. One can say that without overstatement. It is not common for people to weep at a press view, nor to fall silent with awe, but both happened this week at "The Sacred Made Real." El Greco to Velázquez, forgotten sculptors such as Juan de Mesa, are now resurrected for our times. Christ's crucified body emerges from blackness, broken knees bent awkwardly into our space. The impulse is to reach out and touch – "Everyone who sees it," wrote a Spanish contemporary, "believes it to be a sculpture"; amazingly, it is a painting.