Four Corners is a canvas from 1971, a period of maturity in José Guerrero's artistic trajectory, characterized by the affirmation of his own pictorial language in which color and structure acquire absolute prominence. The artist consolidates the "Guerrero system" and begins to grant great importance to the edges and to the zones where some colors coexist with others, transition zones between chromatic fields that become fundamental elements of the painting.

The work is organized as a dynamic space, articulated from its limits, in which color not only constructs the image, but generates an internal vibration that activates the entire surface of the canvas. Guerrero conceives this painting as a field of contained energy, in which the paint seems to expand and contract in direct allusion to the title: four masses of black paint anchor the angles of the canvas, tensioning the composition from its extremes. Around them, a frame of intense yellow—vibrant, almost electric—surrounds a white and luminous field in whose center a gray form descends in a spiral until it resolves, unexpectedly, in a small red stroke. That minimal gesture, almost a wound or a flame, concentrates all the energy of the image: it is the point where the tension accumulated in the four sides of the painting finds its release.

Sempere acquired this canvas in the context of Guerrero's individual exhibition at the Juana de Aizpuru Gallery in Seville in 1976, or through direct exchange with the artist. What is certain is that it traveled directly to Alicante in October 1977 together with the work by Fernando Zóbel that is kept in the collection.

This work belongs to a specific moment in the evolution of Guerrero's artistic practice. It is a period in which the artist consolidates what can be called the "Guerrero system". It is then that he begins to grant great importance to the edges, to the borders, to the zones in which some colors coexist with others. It is then that he definitively realizes that more than the action itself—which will still occur—what matters is that color flows, that the painting breathes, that the painting is like a boxing ring, tensioned on all four sides, vibrant, luminous, charged with energy. (Bonet, Guerrero, 1994, p. 35).

In the physical and technical aspect of his works, Guerrero approaches the canvas in a very concrete way, preparing the fabrics: "I have been preparing canvases since I was very young. I have come to take sheet fabrics, nail them, and apply a coat of glue. The artisans from Granada taught me, saying: 'You take rabbit glue, add a drop of honey, put it in a water bath and when it's ready, like confectioners do, when the little ball sticks to you that's when you can use it, because if not it will crack on you. I have almost never painted on commercial canvases. I like the fabric to have a certain corporeality.' Guerrero does not attack the canvas directly, contrary to what one might think when observing his painting: 'I prepare sketches. I spend summers making sketches and I always use them to work with the canvas, except during the expressionist period, in my early years in New York, when it was more spontaneous painting, gestural, seeing what happens, you know?, but now it's more important to know what I want to do or to have an idea of what I want to do. So when I stand in front of the canvas I already have a first idea and I usually take a piece of charcoal and make some strokes, nothing more, and I begin with the color stains which, in the end, usually have nothing to do with the sketch, I keep the sketch in front of me so as not to lose my way, and above all, to not stray from my line, to keep sustaining myself, and the moment I apply the first color, it's already a battle, that doesn't stop. As for the use of color and its application, Guerrero maintains a special relationship with color ranges: 'Black is a color of tragedy, but for me it has something familiar about it, I already told you that we have been dressed in black our whole lives, my father died when he was forty-two years old and until he was ninety-three he never took off his mourning clothes, black for me, perhaps it is the color of colors. Yellow is the field, the wheat fields. White is Andalusia, nothing more. The dazzle of a whitewashed wall.' 'I begin by applying color in a very liquid way. Sometimes it drips. I dissolve it with turpentine essence, then, to finish it, I use a technique that seems the Baroque painters used, well, this is nonsense, and it consists of a bit of oil, varnish, dammar and turpentine essence, but anyway, sometimes I don't even use it, only when something absorbs too much.' (conversations with Guerrero, p. 145-146)