to connect the "heart shape" as it evolved in the Late Middle Ages with instances of the geometric shape in antiquity. Such theories are modern, proposed from the 1960s onward, and they remain speculative, as no continuity between the supposed ancient predecessors and the late medieval tradition can be shown. Specific suggestions include: the shape of the seed of the silphium plant, used in ancient times as an herbal contraceptive, and stylized depictions of features of the human female body, such as the female's breasts, buttocks, pubic mound, or spread vulva. Renaissance and early modern Heart shapes can be seen on various stucco reliefs and wall panels excavated from the ruins of Ctesiphon, the Persian capital (). The Luther rose was the seal that was designed for Martin Luther at the behest of Prince John Frederick, in 1530, while Luther was staying at the Coburg Fortress during the Diet of Augsburg. Luther wrote an explanation of the symbol to Lazarus Spengler: "a black cross in a heart, which retains its natural color, so that I myself would be reminded that faith in the Crucified saves us. 'For one who believes from the heart will be justified' (Romans 10:10)." The aorta remains visible, as a protrusion at the top centered between the two "chambers" indicated in the symbol, in some depictions of the Sacred Heart well into the 18th century, and is partly still shown today (although mostly obscured by elements such as a crown, flames, rays, or a cross) but the "hearts" suit did not have this element since the 15th century. Modern Since the 19th century, the symbol has often been used on Valentine's Day cards, candy boxes, and similar popular culture artifacts as a symbol of romantic love. The use of the heart symbol as a logograph for the English verb "to love" derives from the use in "I ♥ NY," introduced in 1977. Heart symbols are frequently used to symbolize "health" or "lives" in video games. Super Mario Bros. 2 (1987, 1988) had a "life bar" composed of hexagons, but in 1990s remakes of these games, the hexagons were replaced by heart shapes (the Castlevania franchise being a notable exception, where the hearts are ammunition for the secondary weapons instead of representing health). Since the 1990s, the heart symbol has also been used as an ideogram indicating health outside of the video gaming context, e.g., its use