From pre-phylloxera vines.
I sipped this next to a bottle of the 1979 which has long been a favorite of mine. The nose on the 1979 was much more expressive, the nose on the 1923 was rather reticent (from a small Riedel cognac glass). However the palate of the 1923 was remarkable and left the 1979 in the dust, making it seem a bit clumsy in comparison - which was definitely not my impression before tasting it side by side.
The flavor expands in a perfect expansive cloud of spring flowers and warm spices. Wow. I had questioned my sanity in buying this bottle last year but now I don’t regret it.