It is much more complicated than that. First, I must agree with Francis Croissant, whom I admire and respect, in
LIMC that
Hygieia and
Salus are not the same. This distinction is complicated by Hadrianic and Antonine use of
Hygieia motifs for
Salus, occasionally. Second, I must repeat that 'patera' is a very generic word and by no means limited to religious applications; when it is used in a text to translate Greek
phiale, it is a very approximate translation and not much of a clue to whether
phiale was the word in the original (therefore I applaud the
German scholars who write 'Schale' instead, or English who say 'dish', words that translate the generic character of
patera.
Phiale (LS), after
Homer, is 'a broad, flat
bowl, used for drinking or pouring libations (Herodotos and in Attic Greek). Although
patera is as close as you can come in Latin, the shape called
phiale is designed to minimize sloshing.
In
LIMC I found (to keep this short) that the iconography of
Hygieia is vague (because she is a personification, doubtless), that the iconography of
Salus is not quite the same, even in the Imperial period, that (as I suspected) the
types on Greek Imperials reflect the Asklepieia at
Pergamon and Epidauros.
You will have perceived that a
phiale mesomphalos with that bump in the center might be read as an
egg in the center. To that I would only say, then it would have to be called a
patera (shape of a broad soup
dish) rather than a
phiale. That if the figure was pouring from it, it preferably would have to be called a
phiale, especially if it was held phiale-fashion. That when the goddess,
Athena or
Hygieia feeds the
snake lumps (eggs would be OK), it is with her fingers, not out of any kind of
dish. Finally, what came as a surprise to me, the name
Hygieia begins in the early 5th century as an epithet of
Athena on the
Athens Acropolis, and only when the
Athens Asklepieion is opened does she become first the companion, then in the fourth century the daughter of
Asklepios. She has no more myth of her own than little
Telesphoros has. Besides, almost all the
statues lack their original
hands, with or without dishes of any kind, and
Hygieia has no
snake until she gets one, so to speak, from
Asklepios. The earliest statuary
type is that known as the
Hope Hygieia, after the former owner of the statue now in Los Angeles.
Salus doesn't have one nearly so early, and when she gets one it is patently Greekish.
Hygieia means
valetudo in Latin. Consider
Salus Publica. That isn't
Valetudo Publica. A valetudinarian, even in modern derivation, is not the same as a salutarian.
In other words, I'll write to Geraldine Gesell about the milk business, because
LIMC only talks about what you can see, because from the iconography all that is certain is that (i)
Hygieia feeds
snake lumps, and (ii) you can pour a libation from a libation
dish for almost any deity.
Patricia LawrenceP.S. You'd think with textbooks all over the house I could lay
hands on the vase-shapes plate, but here is the shape of a
phiale in section, with the (actually commoner) mesomphalos
type in
red. As soon as I find a photo of the Boston
Phiale, the namepiece of the
Phiale Painter, I'll post it.