According to scholarly analysis and criticism, Callus’ academic and intellectual endeavour is divided between his ‘Malta Period’ (1912–1931) and his ‘Oxford Period’. His publications from the first period, though interesting, are not of much interest to philosophy.Classified in Daniel Callus: Historian & Philosopher, Mark Montebello, Malta University Press, Malta, p. 141. His best scholarly contributions are all part of the latter period. They are not very numerous in number – just 40 contributions – but all of a very high calibre, both scientifically and, sometimes, philosophically. These works are generally distinguished under three main headings, as indicated hereunder:
