The concept of "rebirth" was certainly contemporaneous, and as lox states above involved the study of all things ancient (not exactly rediscovery - the Holy Roman Empire was in many respects a persistence of the Western Roman Empire (i.e excluding the Eastern, based in Constantinople) - but rather a study that gained force over decades and centuries), including manuscripts, and architecture and sculpture. The Sorbonne in Paris was particularly noted for the study of Aristotle. Definite borrowings from ancient sculpture may be found in the work of the Pisani from the mid thirteenth century, and in fact it's been shown that the "vocabulary" of sculpture in particular, as practised i fifteenth-century Italy, can invariably be traced to Antique prototypes. As Amos mentions too, there was a combination of many, "non-artistic", factors too.