Clay is one of the timeless materials in Western manufacturing traditions, versatile and deeply-rooted. All great civilisations of the past, from millennial China to the empires of the sacred lands of the Pharaohs, and Hammurabi's and Nebuchadnezzar's Babylonia, used adobe for construction purposes.

The biography of art is inextricably linked to this material, baked from clay and other sedimentary rocks, and coming to life by a merger of the four elements – fire, earth, water and air – with which the pre-Socratic philosophers explained the constituent ingredients of nature.

Household objects like bowls, vases, fountains; decorative items like porcelain from Meissen, Limoges, Alcora; and great monuments such as Agrippa's Pantheon, the Madinat al-Zahra, the Amsterdam Stock Exchange or the National Museum of Roman Art in Mérida, all point to the broad functional scope of this material, capable of being acclimatised to any place, scale, time and geometry.

Brick is present in pre-Colombian architecture, in Mesopotamian, Egyptian, Greek, Roman, Byzantine and Islamic architectures... surviving in urban buildings even when Rationalism and Industrialisation began questioning ancient craft practices.

The idyllic relationship between architecture and ceramics invariably gave rise to transgressive proposals from such competent hands of proven experts such as Petrus Berlage, Rafael Guastavino, Frank Lloyd Wright, Alvar Aalto, James Stirling, Louis Kahn, Aldo Rossi, Robert Venturi, Alvaro Siza, Antonio Fernández Alba, Francisco Javier Sáenz de Oiza, Rafael Moneo, Enric Miralles,…

Few materials have survived and adapted themselves so successfully to all the successive formal revolutions occurring throughout history, from the fanciful, decorative richness of Mannerism to the analytical rigour of Neo-Classicism; from the theatricality of the Baroque to the nineteenth-century triumph of Spain's Neo-Mudéjar style.

The mosaic for the high altar of the church of San Nicolás sitting in the port of Gandía, included in the Iberian Docomomo, is a magnificent piece of narrative jewellery – an authentic spatial canvas on which coloured earthenware contributed all the warmth of the earth.

Designed by the architect Gonzalo Echegaray Comba and the engineers Eduardo Torroja Miret and Joaquín Nadal Aixalá, the parochial complex, which includes a freestanding bell tower, a cloister and an abbey house, is located in a privileged place in the port of the capital of the district of La Safor.

The temple has a single nave and a trapezoidal shape that converges towards the chancel, facing east, so that it is bathed by the rising sun at the start of the day, symbolising the Sun of Health, Sol Salutis, whereas in the evening it receives the Sun of Justice, Sol Justiciae.

For its creators, the sculptors Nassio and Andrés Cillero, the doctrinal and ritualistic reasons explaining this orientation refer to Heliopolitan theology, already present in the sanctuaries of Thebes (Luxor, Karnak, ...) dedicated to the sun god and the life of Ra.

Hence the symbolism of this antithesis between east and west, the dichotomy between light and darkness, and good and evil, all find their moralising interpretation in the mural, evoking the personal cosmic liturgy of the artist.

The large volume of the church, widened by six chapels on the Epistle side, produces a structurally modulated figurehead. A sequence of bare reinforced concrete ribs sustain two independent sheets that are separated to produce a lateral strip window on the north side, making an asymmetrical cross-section that illuminates the main body from above.

This solution, both of a central shell and end walls, is reminiscent of the pediment of Recoletos, which Torroja designed in 1935 with Secundino Zuazo. The powerful rhythm of the structural grid contributes to a truly expressive spirit and reinforces the typological clarity of an interior devoid of ornamentation, where Nassio faced one of the biggest challenges of his life.

Of note is Torroja's iron will to innovate both geometrically and formally as he continued the path taken by the Swiss Robert Maillart, the Frenchman Eugène Freyssinet and the Italian Pier Luigi Neri, with which he contributes to dramatic breakthroughs and improvements in reinforced concrete.

The commission was made to Nassio at only 27 years of age, but his memory was full of polychrome terracotta models that he so frequently observed on visits to the National Etruscan Museum during his stay as a student in the eternal city.

He was fascinated by Roman mosaics and the generation of tessellations by way of geometric transformations. He showed great interest in the studies of regular polygons – Archimedes – and Platonic solids – Kepler.

He spent time delving into the processes of moulding, drying, firing and placement, into the knowledge of tools and other stereotomic practices. But above all, after being captivated by the solvency and security of his preparation techniques, he prepared an authentic opus tesselatum, reusing leftovers from quarries and workshops, and juxtaposing opus incertum with opus reticulatum for greater regularity.

This double empirical and epistemological method helps us to understand the constructional experience of the sculptor, who craved to recover craft traditions for modern architecture.

In addition, his début as a large-format mural artist in 1959 forced him to reflect on philosophy and sacred art, at a time when thinking deprived symbols of any metaphysical moorings.

Nassio conceived the ceramic altarpiece in the knowledge that clericalisation of worship in the 19th century increasingly distanced the faithful in liturgy, bringing about the birth of regenerative currents within the church after the First World War seeking to eradicate deviations and achieve a doctrinal aggiornamento.

These movements culminated in the famous speech of the Pope at Assisi (1956) heralding the way for the celebration of an ecumenical council. That tumultuous period of change and reforms brought a crisis to the ancestral morphology of the Christian church, questioning the role and significance of its most important components: chancel, altar, pulpit, apse, choir, baptistery, ...

The exhaustion of the historicist approach brought new models to Spain as from the 1950s, despite the delay due to the misanthropy of the regime, immersed in the rebuilding of its severely damaged ecclesiastical heritage.

The medieval mysticist notion of beauty as splendor veritatis and the perception of images as divine revelations were now quite distant. It seemed that Nassio addressed this project by rejecting a literal interpretation of traditional schemes, conceiving religious space from an ethical perspective, and diving into all the heterodox typological sources offered by sacred architecture of the 20th century.

Greater influence was wielded by Francisco Javier Sáenz de Oiza, who from 1950-1954, along with Luis Laorga, built the Marian shrine of Our Lady of Aránzazu in Oñate, and in 1954 received the National Architecture Award for his proposal for a chapel on the Road to Santiago, in collaboration with José Luis Romaní Aranda and the sculptor Jorge Oteiza.

Sáenz de Oiza returned with excitement, as later occurred with Nassio, from all the technological advances of the American way of life, whose benefits he incorporated into his teaching.

In this context, the main altar of San Nicolás de Bari preludes the early maturity of its author, who consecrated a personal mélange that brought geometric-structural essentiality into the apparently physiological.

Nassio presents a continuous and colourful abstract vision (Einfühlung) in the form of a gigantic cosmic altarpiece of the heavenly vision given in the Scriptures, with the temple being understood as the threshold of paradise, the true symbol of the Kingdom of God on Earth: all in all, a City of God, a heavenly Jerusalem evoked in the passages of the Apocalypse.

The mural portrays a strict interpretation of an architectural pattern, generating a succession of shapes and planes that are faithful to Christian quaternary symbolism, with which Nassio offers his particular interpretation of the Cosmos.

The temporal affinity – the four seasons – and the spatial affinity – the four points of the compass – of the quaternary pagan scheme facilitates the interpretation of the colourful mural, which is a true paradigm of the unitary conception of creation.

The whole chapel thus announces a Biblical discourse whose iconographic patterning is provided by the ceramic filigree abounding in astrological and zodiacal references to the four elements, to the four cardinal virtues, the four horsemen of the Apocalypse, and the four rivers of Paradise, ...

Nassio uses these to recreate his cosmos-like tetramorph, taking inspiration from the vision of the prophet Ezekiel, who anticipated the four zoomorphic angels of the Revelation of St. John, brought from the East, and protecting the Pantocrator.

The figuration is sinuously diluted to define a wall that refers to solar symbolism of the oculus or all-seeing eye representing Divine Providence, the protective purification of all believers.

The result is a ceramic tapestry, as a narrative support to ideas linked to its original ritual character, transcending and underlining the structural lines of the sanctuary, and reinforcing, as Le Corbusier did at Ronchamp, the analogous representation of the ark of the Judeo-Christian salvation (Noah).