score:5
"The very past" and "especially Victorian era" does not mix well, so it is unclear what era you are looking at.
"The very past" would, in my interpretation, be something like the Venus of Willendorf and other palaeolithic sculptures emphasizing breasts. Whether that is to indicate sexual attractiveness, or fertility, or if there is indeed a difference between the two for such early times, I leave open to interpretation.
Somewhat newer would be the Song of Solomon (e.g. 4:5 "Thy two breasts are like two young roes that are twins, which feed among the lilies.").
Breasts are part of the sexual dimorphism of humans. Among other traits they define what we perceive as "female", like we perceive a muscular, breast-less upper body as "male". As such, it would be quite unnatural for a heterosexual male of our species to not perceive breasts as "sexy". Whether the preference is for them to be large or small, hidden or displayed, that certainly changed over time and under cultural influence.
Upvote:2
The 1001 Nights, collated from Middle Eastern folk tales quite a while before Victorian times (first English-language edition (c. 1706β1721)), is absolutely rife with descriptions such as her breasts were like ripe pomegranates.
Or look at Angkor Wat, Cambodia, 12th century, sculptures. Seems pretty clear to me that breasts are emphasized.
Looks like someone had a pet theory with some valid grounding that they tried to fit too much into.