An "unintended" state of a map in the form of plate damage can also help in determining its age.
In this case plate damage consists of a crack which began to form in the cartouche of the continent map of Africa after 1602 and which progressively widened with each subsequent edition.
The Theatrum was an instant success and four issues of the first edition were published in 1570.
When it appeared, it was the most expensive book ever printed.
It was not until 1624 that the tables finally appeared in the last edition of Ortelius' Parergon, produced by Plantijn-Moretus. The Roman world ends in the east with the river Ganges and island of Ceylon. The first and most obvious reason for discarding a plate and replacing it with a new one is increased geographical knowledge.
To demonstrate the importance Ortelius attached to these tables, consider his final piece of text accompanying them (translated from Latin): "Farewell dear spectator and dear reader, enjoy this monument which, although it has plenty of shortcomings, does not have an equal or even anything like it under all the relicts from antiquity". Knowledge of the world expanded at a tremendous pace during the life cycle of the Theatrum and examples where incorrect information leads to correction by introducing a new plate are plentiful.
Clearly, many new plates were introduced and only a few cast aside.
As a true humanist and renaissance cartographer, Ortelius was keenly interested in the geographical knowledge of classical antiquity.
They show the Roman world view around the third century.
The original, found by Konrad Celtes (1459-1508) in a library in Augsburg, came into the hands of Konrad Peutinger (1465-1547) and later went to his relative Marcus Welser.
These formed the basis of his Peutinger tables in four sheets.
Proof prints from these plates went back to Marcus, were compared with the original and corrected accordingly.
The Parergon maps, which he considered his major cartographical achievement, bear witness to this.