Paintings by Guido Cagnacci can be viewed in museums and collections across Europe and North America. In Corsica, his work *Midas at the Source of the Pactolus* is held at the Musée Fesch (Ajaccio). In the United States, one can find Cagnacci's paintings at the Baltimore Museum of Art (Moses Sweetening the Bitter Waters of Marah), the Museum of Fine Arts in Boston (Mars and Venus), and the Detroit Institute of Arts (Diana and Endymion). In Europe, Cagnacci's works are held at the Musée des Beaux-Arts, Caen (Venus with the Dead Adonis); the Royal Museum of Fine Arts, Copenhagen (Moses and the Burning Bush); and the Hermitage Museum, Leningrad (The Deposition).

Guido Cagnacci (1601-1663) was an Italian painter of the Baroque period. While he was active, the art market saw an increase in the production of prints of single paintings, and illustrated books advertising collections became more common. One such collection was that of Vincenzo Giustiniani, who had prints made of the sculptures in his collection. From about 1633, artists lived in Palazzo Giustiniani, and prints were produced in a systematic way. The prints were to be sold to raise money for the poorest members of his family. The collection was never to be broken up and sold; it was to be kept together "per mia memoria perpetuamente". Collectors of the period sometimes obtained certificates of authenticity for artworks, but these were not always reliable.

Guido Cagnacci (1601-1663) was an Italian painter whose work provides insight into the artistic dialogues of the Baroque era. He is known for his ability to synthesise different stylistic approaches. Cagnacci's paintings often combine elements derived from other artists. For example, in his depiction of Saint Catherine, he modelled the saint after Raphael's Saint Cecilia, while the executioner was rendered in the realistic style of Caravaggio's figures. This method of combining stylistic references is a significant aspect of his artistic approach. His work also anticipates later developments in painting. His study of antique sculpture, particularly his focus on the head of Seneca, foreshadows similar analyses undertaken by Nicolas Poussin and François Duquesnoy. Poussin later overtly referenced Cagnacci's technique of combining modern styles in his own work, such as Rebecca and Eliezer at the Well. Cagnacci's manipulation of styles and gestures would have appealed to Poussin.

Guido Cagnacci's painting techniques involved a combination of traditional methods and innovative approaches. Like many artists of his time, Cagnacci employed oil-based binders, particularly linseed oil, for his pigments; however, some of his works also show evidence of mixed media, such as the addition of egg tempera to the oil paint. This technique, known as fatty tempera, may have been used to modify the colour layers and achieve specific optical effects. Cagnacci's application of paint was typically thin and direct, aligning with practices seen around the 1550s. Unlike some of his contemporaries, such as El Greco, Cagnacci did not favour coarse bristle brushes or thick impasto effects. Instead, he preferred soft, fine brushes and a fluid oil medium to achieve smooth surfaces and detailed renderings. This approach allowed for delicate highlights and careful attention to detail, contributing to the distinctive look of his paintings.

Guido Cagnacci's work had an impact on Nicolas Poussin. Poussin was drawn to Cagnacci's skill in using styles and gestures to create emotional impact. Cagnacci studied a head of Seneca, and his rendering of the figure's wrinkled neck later appeared on Poussin's Saint Peter and Joseph, denoting their age. Poussin analysed ancient sculptures, and Cagnacci provided an important precedent for this. Later in his career, Poussin created Rebecca and Eliezer at the Well in direct competition with Cagnacci, overtly referencing Cagnacci's technique of combining references to individual modern styles. Poussin's painting was a critique of Reni's Sewing Madonna, and Poussin succeeded in combining the different lovelinesses of women painted according to a variety of artistic ideals with narrative clarity of expression, unified in time and space.

Guido Cagnacci's artistic development saw a convergence of influences. Although documentation of his early training is sparse, it is believed he absorbed elements from diverse sources. Caravaggio's naturalism and dramatic use of light had an impact, as it did on many artists of the period. Cagnacci's paintings sometimes display a similar tenebrism, with strong contrasts between light and shadow. Beyond Caravaggio, Cagnacci appears to have studied Bolognese painting. The Carracci academy, with artists such as Ludovico Carracci, promoted a classical style, and it is likely Cagnacci was exposed to these ideals of balance and idealisation. Guido Reni, another prominent Bolognese painter, also provided a model. Reni's work blended classical elements with emotional expressiveness, and Cagnacci seems to have adopted a similar approach. Exposure to Venetian art also shaped Cagnacci's style. The Venetian school was known for its use of colour and sensuality, and these qualities appear in Cagnacci's later works, particularly after his move to Venice. Bernardo Strozzi, active in Genoa and later Venice, further popularised Flemish techniques.

It is difficult to name one single work as Guido Cagnacci's most famous. He produced religious scenes and allegories, as well as portraits and genre pieces. Guido Reni, a fellow Baroque painter from Bologna, is known for his altarpieces and frescoes. Reni's "Slaughter of the Innocents" (1611-1612) is based on the biblical story from the Gospel of St. Matthew. King Herod, feeling threatened by the news of the newborn Christ, ordered the death of all male children aged two and under in Bethlehem. Reni's painting, now in the Pinacoteca Nazionale in Bologna, depicts this event with a combination of realism and idealised forms. The painting uses colour contrasts, such as the red, blue, and gold draperies against the grey tones of the dead infants. Two putti hold palms of martyrdom, representing the rewards the victims will receive in Heaven. The work was well received, and Giambattista Marino wrote a poem praising it.

Guido Cagnacci is associated with the Baroque style, which broadly dates from 1600 to 1700. The term "Baroque" may come from "barocco", the Portuguese word for an irregular pearl; it was later used to describe art that is full of emotion, dynamism, and drama, often with strong contrasts in tone. Baroque emerged in response to religious tensions in Europe, particularly to reinforce Catholicism. The Council of Trent (1545-1563) determined that religious art should encourage piety through directness, accuracy, realism, and logic. The Baroque style, which began in Italy and spread to other countries, aimed to be visually and emotionally appealing and to focus on Catholic doctrine in order to educate and influence. Baroque artists interpreted stories realistically, but with individual approaches. Their work is exuberant and intense, featuring believable figures and human dramas. The style inherited movement and emotion from Mannerism, while taking solidity, perspective and classical lines from the Renaissance. Two significant aspects are the use of contrasts between light and shadow and close observation of textures.