The practice is not well understood, although it has long been claimed to be part of indigenous culture from time immemorial (well, from Ezekiel's time,1 anyway!) up to the present day.
From antiquity, the evidence from Galen is often cited (see, e.g., Keil below). It comes up in his De sanitate tuenda, often known in English as "Galen's Hygiene". The relevant passage is found in Bk. V. 4,2. Forcada (see below) offers this translation by H.E. Sigerist:2
The newborn infant, then, free from defect in his entire constitution, should first be powdered moderately [with salt]a and wrapped in swaddling-clothes, in order that his skin may be made thicker and firmer than the parts within. For during pregnancy everything was equally soft, since nothing of a harder nature touched it from without, and no cold air came in contact with it, whereby the skin would be contracted and thickened, and would become harder and denser than it was before and than the other parts of the body. But when the baby is born, it is necessarily going to come in contact with cold and heat and with many bodies harder than itself. Therefore, it is appropriate that his natural covering should be best prepared by us to exposure.
a. συμμέτροις ἁλσὶν περιπαττόμενον = summetrois halsin peripattomenon
Rashi's comment on Ezekiel 16:4 displays this understanding, and seems to imply it is a current custom in his own day (12th C. France):
From here it is derived that we salt the newborn so that his flesh hardens.
C.F. Keil's 19th century commentary echoes Rashi's and adds an ethnographic dimension:3
After the washing, the body was rubbed with salt, according to a custom very widely spread in ancient times, and still met with here and there in the East (vid. Hieron. ad h. l. Galen, de Sanit. i. 7; Troilo Reisebeschr. p. 721); and that not merely for the purpose of making the skin drier and firmer, or of cleansing it more thoroughly, but probably from a regard to the virtue of salt as a protection from putrefaction, "to express in a symbolical manner a hope and desire for the vigorous health of the child" (Hitzig and Hävernick).
Daniel Block's magisterial Ezekiel commentary extends the possible rationales for the practice to include:4
- hygiene, including cleaning and strengthening the baby's skin;
- a spiritual function, warding off evil spirits ("apotropaic"); and
- a different hygienic function, this to do with preventing the souring of the infants "swaddling cloth".
Rashi's notion, shared with Galen, still visible in #1!
More recently, this gets rehearsed by Jennie R. Ebeling, Women's Lives in Biblical Times (T & T Clark, 2010), p. 103, who adds reference to specialist bibliography. To that might be added an older and a newer study:
Forcada's study offers the most full and careful historical study of the practice I'm aware of. All this suggests a fairly consistent picture of a widely dispersed practice which is ill understood, but which persists in any case.
Linguistic addendum : this practice forms part of a list of newborn care that this neglected foundling did not receive. The Hebrew formulation is וְהָמְלֵחַ לֹא הֻמְלַחַתְּ wəhomlēaḥ lōʾ humlaḥat = "you were not salted", an "infinitive absoloute + finite form" construction,5 the denominative verb based on the noun מֶ֫לַח melaḥ "salt".
The lexica are not a lot of help here. The venerable Brown-Driver-Briggs, p. 572a simply reports this (unique) occurrence (the entry notable for including a rare typo in the headword!); Jastrow's Dictionary of the Targumim, the Talmud Babli and Yerushalmi, and the Midrashic Literature, on p. 788a-b relates the term exclusively to the treatment of raw meat (and hides) and fish -- not an infant in sight. FWIW.
- Ezekiel's oracles date from 593-571 BCE.
- M. Forcada, "Salting Babies: Innovation and Tradition in Premodern Procedures for Neonatal Care", Suhayl 11 (2012): 157.
- C.F. Keil, Biblical commentary on the prophecies of Ezekiel (T & T Clark, 1876; German original 1868), p. 197.
- D.I. Block, Ezekiel 1-24 (Eerdmans, 1997), p. 475.
- This gets a fairly full explanation in an earlier Q&A on the use of this construction in Genesis 2:16.