The vendor shall be responsible for warranty against the hidden defects which the thing sold may have, should they render it unfit for the use for which it is intended, or should they diminish its fitness for such use to such an extent that, had the vendee been aware thereof, he would not have acquired it or would have given a lower price for it; but said vendor shall not be answerable for patent defects or those which may be visible, or for those which are not visible if the vendee is an expert who, by reason of his trade or profession, should have known them. (1484a)