Many of the paintings from this period depict specific historical subjects, while others were genre scenes or portraits. This development towards Realism made him one of the pioneers of this artistic movement in Belgium. The painting ’'Wedding in Flanders in the 17th century" (1839; Royal Museum of Fine Arts Antwerp) was the first to herald this more sober style. His works from the 1640s attest to Leys' search for historical and psychological truthfulness, which replaced the emphasis on pathos and sentimental anecdote of his earlier work. An example of his works that abandoned historical legend in favour of a realistic depiction of historical events is the composition "Albrecht Dürer visiting Antwerp in 1520". Leys based this picture on the account given by Dürer in his own journal of the event. In his scenes of 16th and 17th-century Antwerp, Leys sought to reflect the spirit and atmosphere of that time. His compositions of historical events and of everyday life were realistic and may have been inspired by contemporary French Realists Gustave Courbet and Jean-François Millet.