Career
Following the custom of Belgian students he did not confine himself to the courses at Catholic University of Leuven (French: Louvain) but went to Paris to hear Julius Oppert, Émile Egger, and Henri Patin, and to Berlin, Utrecht, and Leyden, where he followed the courses of Cobet. The first work is a handbook which stops at Constantine I in the first three editions and now goes as far as Justinian I. The author combined systematic and historical order by dividing the history of Roman institutions into "epochs" and "periods", viz., epoch of royalty, epoch of the republic, epoch of the empire, subdivided into the period of the Principate and that of monarchy. In each of these sections Willems studies the conditions of persons, government, and administration.
The book on the Roman Senate shows more evidence of personal research.
lieutenant contains a new opinion concerning the recruiting of the Senate. Willems does not admit that there were plebeian senators in the century following the expulsion of the kings.
lieutenant was by the exercise of the curule magistracies that the plebs entered the Senate, in fact after 354-200. A plebiscite proposed by the Tribune Ovinius and accepted at the end of the fourth century hastened the introduction of the plebeians, and, in short, made the Senate an assembly of former magistrates.
He also contributed to the Bulletins of the Brussels Academy a memoir on the municipal elections of Pompeii (1902).
He belonged to the Flemish party and collected materials for a work on the Flemish dialects, which remains unfinished.