The Archaic Didymaion

by Jan Sammer

Tradition ascribes the founding of the oracular temple of Apollo at Didyma to a young Milesian goatherd named Branchus, who used to pasture his flock in the rolling hills south of the city of Miletus. The boy was of such exceptional beauty that Apollo himself became enamoured of him, met him by a spring and kissed him tenderly. To mark the spot of their encounter, the god planted a bough of bay in the ground and as a token of his affection placed on the boy’s head a crown of bay leaves. This divine gift bestowed on the boy the power of prophecy. His mother then recalled an odd vision she had seen in a dream many years earlier, when she was pregnant with the boy: it seemed to her as if the sun entered her mouth and emerged from her womb.

Branchus' mother, the daughter of a prominent citizen of Miletos, was married to Smikros, a Delphian by birth, brought to Miletos by his father Democlos at the tender age of thirteen at the command of an oracle. Separated from his father by a stroke of ill fortune, he was found, weeping and disconsolate by the son of the goatherd Epitharses. Hearing the boy’s tale of misfortune, Epitharses took him under his roof and raised him as his own son.

One day, as the the two boys pastured their goats, they saw a beautiful white swan, which they chased down and captured by throwing a cloak over it. As they argued which one of them should bring it as a gift to their father, their argument turned into a fight. At length, exhausted by the struggle, they removed the cloak, but instead of a swan, they found a woman. Overtaken by fear the boys began to flee, but she called them back, revealing herself as Leucothea, the White Goddess. The fight she had witnessed had pleased her, she told them; now they were to go and tell the Milesians to institute a regular athletic contests of boys in her honor. The encounter with Leucothea brought immense prestige to Smikros, and the honor of marrying the into one of the leading families of Miletus. When his wife was pregnant with their first child, she had the dream vision described earlier, which indicated a great destiny for Branchus, her firstborn.

Branchus established a shrine to Apollo at the sacred spot of his encounter with the god; the bough that the god had planted here next to the spring grew into a sacred grove a bay trees. When Apollo later became wroth with the Ionians and sent a plague against them, only Branchus was able to purify them: sprinkling the multitude with boughs of bay, he bade them chant a magical hymn to Apollo and his sister Artemis.

As the renown of Branchus’ prophetic shrine spread throughout Ionia, Leodamas, the last king of Miletus, dedicated to it a tithe of the spoils from his triumphal campaign against Carystus. These included a woman from Carystus with an infant at her breast, whom Branchus took as his wife, adopting the child as his own son. As the boy grew in a miraculous way and exhibited an intelligence beyond his years, Branchus made him a herald of the prophetic responses, naming him Evangelos. When Evangelos grew into manhood, he inherited the oracle of Branchus, and since then the oracular powers were passed on through the generations from father to son.

The Archaic Didymaion was an octastyle Ionic temple; hence, if it was to be eustylos according to Vitruvius's definition (111.3.7) its front had to be divided into 24.5 parts, or modules. Calculating in demi-modules (a demi-module being equal to the radius of a column at its base), there were 49 of these on each front. In laying out the ground plan for the stylobate, the most difficult task facing the surveyor was to achieve perfect right angles, since even a small error in angular measurements would result in serious deviations in a structure as large as the archaic Didymaion. The architects solved this problem for the surveyors by making use of Pythagoras’ theorem, which defines the relationship of the diagonal of a rectangular figure to its sides. In order to avoid irrational numbers, they did not use squares, but rather near-squares. The near-square is a rectangular figure whose diagonal and sides are whole numbers or rational fractions of whole numbers.

In the case of the Archaic Didymaion, it seems that two near-squares measuring 50 x 52.5 demi-modules were laid out, using the formula (202 +212)-2=29, with a multiple of 2.5. The diagonal of each of these two squares is 72.5 demi-modules. The original ground plan was thus 50 x 105 demi-modules. Once this ground plan was laid out, the width was reduced by one demi-module to 49, in order to achieve the ideal eustylos proportions of Ionic octastyle temples. Measuring along sides already laid out was an easy task.

In the case of the Archaic Didymaion, it seems that two near-squares measuring 50 x 52.5 demi-modules were laid out, using the formula (202 +212)-2=29, with a multiple of 2.5. The diagonal of each of these two squares is 72.5 demi-modules. The original ground plan was thus 50 x 105 demi-modules. Once this ground plan was laid out, the width was reduced by one demi-module to 49, in order to achieve the ideal eustylos proportions of Ionic octastyle temples. Measuring along sides already laid out was an easy task.

52.5                                                       52.5

The following table gives the reported dimensions of the stylobate and shows the result of dividing these values by the theoretical number of demi-modules. The resulting theoretical value of the demi-module is in a very narrow range indeed.

 

actual size
in mm

size in
demi-modules

first approximation of the value of demi-module in mm.

stylobate width

40890 mm

49

834.49mm

stylobate length

87650 mm

105

834.76mm

The proximity of the two empirically-derived values of the demi-module validates the argument thus far. However, a complication arises when we try to apply to this value of the demi-module a corresponding foot. The best fit is the trimmed lesser foot of 277.4489 mm, since 3 of these feet amount to 832.3467 mm. If this was the value of the demi-module, the resulting stylobate would be somewhat smaller than the reported value; it would have required a proportional adjustment on both the width and the length, as is shown in the following table:

size in trimmed lesser feet

theoretical size, unadjusted

adjustment

theoretical size, adjusted

147

40785 mm

3/8 of tlf

40,889 mm

315

87396mm

15/16 of tlf

87,656mm

Until a convincing explanation is found for the proposed adjustment, the type of foot used must be regarded as an open question; however, as regards the use of the demi-module and the near-square, the argument is simple and conclusive.