Chapter Three centered on how Velázquez thematized mechanical skill, or, to put it another way, the artist's touch. The delicacy of his touch is eloquently articulated by the spark-like brushstrokes animating the surface of Las Meninas (Fig. 35), or by the actual painted sparks that appear in The Forge of Vulcan (Plate 4). Touch is implicit in some of these paintings in other ways as well, both in terms of the representation of touching, and through iconographic allusions to touch, erotic touch in particular. Velázquez did not investigate the communicative value of touch nearly to the extent Rembrandt did, but skillful and erotic touch are both at play in the story of Venus, Mars, and Vulcan. Velázquez made The Forge of Vulcan, Mars (Fig. 43), and The Rokeby Venus (Plate 5) over the span of many years, for different venues, but these paintings are all driven by the same narrative, and they all emphasize the critical role of touch in propelling that story.

Aside from Vulcan's firm grip on his tools and materials, The Forge of Vulcan does not emphasize touching directly. The attentive viewer's mind, though, inevitably remembers that Apollo discovered Mars and Venus in an erotic embrace, and recalls how that discovery led to the dramatic moment depicted in this painting, and to Vulcan's clever response. Touch may have been associated with physical skill, as discussed in Chapter Three, but it was also among the material and most dangerous of the senses because of its connection with sex.