Our historical analysis shows that the construction of the present concept of electromagnetic field took place in three periods, or phases, which I will call: (1) ‘heuristic guide’, (2) ‘elaborational’, and (3) ‘philosophical’. The contributions of Faraday and of Maxwell, until his third paper, come under phase (1); those of Maxwell, beginning with the third paper, and of Lorentz, under phase
... [Show full abstract] (2); and those of Einstein fall under phase (3). The reasons for these groupings and for the choice of name for each phase will become apparent as we discuss the relevant details that have emerged from the historical analysis.