This sketch closely resembles Parmigianino’s completed painting of the Conversion of Saul, commissioned by an unknown Bolognese patron and now in Vienna (see illustration). The rapid execution in chalk using broad hatching and leaving numerous changes, known as pentimenti, demonstrates the primacy of drawing in Parmigianino’s working practice. It appears that the artist drew the muscular rearing horse first, as Paul’s head and arm dissect the horse’s leg. The artificial construction of his body through use of stylised curves demonstrates Parmigianino’s economical use of line.
This black chalk drawing is a preparatory sketch for the Conversion of Saul, now in the Kunsthistoriches Museum in Vienna (fig.1). The completed painting is generally dated to Parmigianino’s stay in Bologna, where he stayed for three years following his flight from Rome in 1527. The drawing is often associated with the ink drawing of the same subject (D.1970.PG.360, also on display), and it is possible that Parmigianino was commissioned by Giovanni Bianchi to execute a full-scale painting originating from the ink studies Bianchi may have seen in Parmigianino’s workshop.
The vertically orientated composition on the recto resembles the spatial construction of the Vienna panel. A rapid yet impressively modelled horse rears on its muscular back legs. After drawing the steed, Parmigianino added the fallen body of Saul, his torso and limbs a highly artificial construction of sharp forceful marks and stylised curves: his facial features rendered by single chalk marks that have imprinted through to the verso. A sense of space is obtained by the suggested shadow beneath Saul’s body and the curved lines at the right which correspond to the mountains behind Damascus in the Vienna panel. The apparition of Christ is here represented by jagged lines which extend from the heavens. Parmigianino exploits the softness of the black chalk and the fineness of the paper to allow him to rework the composition at speed; forms are barely suggested, pentimenti are easily made and the buff coloured paper provided a suitable mid-tone for the more modelled composition on the recto.
The lack of a watermark suggests that the drawing was an original component of a larger folio that may have contained other sketches for Bianchi’s commission. On the verso there is a further study for the Conversion, its compositional orientation suggesting that it was executed prior to the transition from a horizontal to vertical composition. Saul is placed at the bottom left, while above him his horse is angled as if to gallop forth from the composition. At the right of the drawing, a horse and rider are seen from behind, likely representing a soldier who gestures towards the heavenly light which appears from the upper-left corner. The forms are barely suggested: single lines and rapid hatching visually manifests Parmigianino’s design process.
Parmigianino drew on his study of existing works when composing Bianchi’s commission. The dynamic motion of Saul’s horse on the verso recalls Pordenone’s fresco of Pilate Judging Christ in Cremona Cathedral, while the barely visible horse and rider also on the verso are identifiable as reversed studies after the horse and rider who gestures to the Bad Thief in Pordenone’s Crucifixion, also in Cremona Cathedral.
Certain elements of the recto demonstrate Parmigianino’s study of the ancient and modern works he would have seen during his sojourn in Rome between 1524 and 1527. The position of Saul’s leg and torso bears close similarities to Michelangelo’s Creation of Adam, which Parmigianino combined with study of Heliodorus in Raphael’s fresco of The Expulsion of Heliodrous. Scholarship has drawn comparisons between the form of the rearing horse with its elongated neck and the sculptures of the Dioscuri installed on the Quirinal hill (fig.4). The placement of Saul in-front of his horse flattens the planar recession of the composition, suggesting a relief-like style reminiscent of antique battle scenes found on Roman tombs. However, the slight revolution of the horse so that both buttocks are visible, is identifiable as a reversed reference to Raphael’s white horse in The Meeting of Leo the Great and Attila (fig. 5), suggesting that Parmigianino consciously enriched his visual references to Raphael through a revivification of the antique and vice versa.
The drawing demonstrates the speed of Parmigianino’s disegno interno and the primacy of drawing in his working methods. Through an economical use of line, he creates studies which are simultaneously a mental exploration of his artistic repertoire and a demonstration of his individual stylistic idiom.
 Vasari, G, Le vite de’ più excellenti pittori, scultori e architettori: nelle redazioni del 1500 e 1568, P. Barocchi and R. Bettarini, eds., Florence, 1994, vol. IV, 539; Lamo, P, Graticola di Bologna: Ossia descrizione delle pitture, sculture e architetture di Detta città, Bologna, 1844, 22.
https://renaissancemodern.wordpress.com/2014/11/18/parmigianinos-studies-for-the-conversion-of-saint-paul-c-1527/ In 1987 a paper backing was removed from the verso of PG.363. This backing was obscuring the sketches on the verso.
 Hall, M, ‘Classicism, Mannerism, and the Relieflike Style,’ in The Cambridge Companion to Rapahel , ed. M. Hall,(Cambridge, 2005), pp.223-36, esp. pp. 232-34. Hall notes that artists following the death of Raphael increasingly turned to Roman sarcophagus reliefs in the flatness of their compositions; Freedberg, Parmigianino, p. 19 Freedberg notes the increasingly relieflike character of some of Parmigianino’s works.