Complex sentence: In his second prestigious commission, the Maddonna of the Snow altarpiece which he painted between 1430 and 1432 for the Siena cathedral, he brings Sienese tradition up to date with a solemn splendor.
Split into simpler sentences: In his second prestigious commission, the Maddonna of the Snow altarpiece which he painted between 1430 and 1432 for the Siena cathedral. He has been said to have brought Sienese tradition up to date with a solemn splendor.