The Piet Mondrian/Hilma af Klint show at the Tate is too busy and too hot and too tiring. af Klint's diagrammatic insistence on Something Beyond is tiring, and besides them Mondrian's pastelly cubist trees are tiring, and the way in an early room there are pictures by each called Evolution and that's meant to prove they had lots in common is tiring, and there'a s room full of drawings and notebooks and vitrines which is tiring and you wish there was a bench and a toilet and a bed. But then as you leave you see, hung high, Mondrian's Lozenge, and you feel faintly through your tiredness a faint glimmer of recognition, as you realise that Mondrian, like af Klimt, is asking you to believe in, no, he is demonstrating the existence of Something Beyond the Visible, and the thing that is Beyond the Visible is God, and it is Mondrian's version of God, which is to say, it is the Right Angle.