Mosaic is a very ancient art, dating to 2500 BC.
At the time of the Mesopotamian civilization, the Sumer used small, enamelled earthenware fragments to decorate columns and walls.
Mosaic technique reached its peak in the V century BC with pebble decorations of floors at Pella, the ancient Macedonian capital.
With the introduction of tesserae cut from stony materials in the III century BC, the use of pebbles was to progressively die out.

The place of origin of the tesselatum is still uncertain. Some sources point to a Sicilian origin, whereas according to others, it would appear to come from Alexandria.
Because of the enormous urban expansion which took place during the Roman Imperial Age, the demand for mosaic floors soared greatly: this set the need for a simpler but decorous ornamentation, suitable for all rooms in the house, the so-called 'black and white technique'.
By reducing the palette to only two colours, mosaic production became more expeditious and less expensive.
A widespread motif in the second half of the century was the use of a plaited strip which, from the edge of the floor, expanded to frame figures into independent medallions.
This motif was so popular throughout the Roman Empire that mosaic copies of the same subject have been found in places very far apart: from Ostia to North Africa, from Antioch to Gaul.

As if ousted from the floor, mosaic was employed for other purposes such as the decoration of fountains, small columns and then vaults: this marked the birth of the opus musivum during the last century of the Roman Republic.
This opus was widely used in the decoration of private houses, where it covered entire walls and small columns, as is the case in the House of Neptune and Anfitrytis at Ercolano. But it was in Ravenna, in the V and VI centuries AD, that, for the first time, this form of art reached its highest expression and artistic independence.
As floor mosaics yielded to mosaics on church walls and vaults, this artistic expression came into direct comparison with painting. The ensuing need for its own identity led to the establishment of a new, decidedly anti-pictorial mosaic awareness and to the search for artistic originality.

Unlike floors, walls can prove a suitable surface to achieve lively and rough effects through a varying tilting of tesserae and an irregular cut. The three-dimensionality of the highly stylised figures gave way to a more linear, bidimensional expression and the composition itself broke down into separate elements, all standing in the foreground.

While on the one hand, these stylistic elements marked the progressive decline of Roman floor decorations, on the other hand they sanctioned the striking success of Christian wall mosaics in the IV and V centuries as they were a perfect medium to express the new religious concepts and the new spirituality in a tangible form.
Even if all the largest existing wall mosaics date back to the Constantinian period, the decorations of walls and vaults with glass tesserae (opus musivum) to embellish Christian religious buildings in all likelihood stemmed from previous pagan examples, of which only rare instances have survived.
As regards the origin of the opus musivum, most scholars believe this technique to be a typical creation of Roman taste and art.

Ravenna, together with Rome, Venice and some areas of Sicily plays a leading role in mosaic art, as in a sense it is a sort of a 'mosaic town' profoundly influenced by this artistic experience throughout its history. The end of the XII century saw the emergence of a new type of mosaic called Cosmatesco.

The decoration was clearly inspired by Arabic motifs. The mosaic consisted of very colourful geometrical patterns, the accomplishment of which demanded considerable effort due to its minute execution.

The technique lent itself to many applications and was used for the decoration of ciboria, jambs, rosettes, architraves and whole floors.
The XIV century saw a shift from the love of decoration that had characterized the previous centuries, thus only rare examples of this art are documented. With the Opicifio delle Pietre Dure (Workshop of Hard Stones) in Florence there appeared the commesso fiorentino or tarsia: special works in hard stones, made up of many small elements shaped according to a particular pattern and set together to form a generally flat, pictorial composition.

The Venetian school in the XVI century brought forth sterile works of art of dubious taste and the same can be said of the Vatican mosaicists, who confined themselves to copying famous paintings.
The Reverenda Fabbrica Pontificia, founded in Rome under the papacy of Urban VIII, led to big but unfavourable innovations. Its main concern was with the reproduction in mosaic form of Vatican-owned frescoes and paintings on wood. This brought about a further degradation of mosaic art, depriving it of its spontaneity and downgrading it to the rank of a cold, static copy.

In the course of the XVIII century, in a period of general decline of mosaic artistic expression, there appeared a form of small and portable mosaic work (mosaico minuto), made for close-up observation, an innovation which bore many similarities with costume jewellery.
The Industrial Revolution in the second half of the XIX century brought an end to all handicrafts involving extensive manual work. Only the mosaics made for the Opera Theatre in Paris did arouse some interest in the technique. Mosaics were set in reverse, with glue on paper.
This method, called 'reverse' or 'indirect', is still in use mainly by the mosaicists in Spilimbergo. The technique allows cost-savings, but to the detriment of mosaic quality, which certainly cannot compare with the superb wall and vault mosaic decorations in Ravenna.

The progressive industrialization of mosaics, with the increasing use of production-line methods, made it possible to employ a less skilled workforce, thus culminating in the almost total decay of the ancient and glorious mosaic tradition.
It was only in the Twentieth century, a period of cultural turmoil, open to experimentation with new artistic techniques, that the expressive power of mosaics was recognized. At the turn of the century, such artists as Antoni Gaudì (1852-1926), Gustav Klimt (1862-1918) and Gino Severini (1883-1966) approached the mosaic and understood its true, intimate essence.
Klimt, who visited Ravenna at the beginning of the century, found in the mosaics of this town the key to a new understanding of the achievements of Byzantine art. Antoni Gaudì, mainly an architect, made use of mosaics for both the interior and exterior of his large buildings. He achieved striking effects in some of his works, such as the Guell Park (1900-1914) and the pinnacles of the twelve cone spires of the Sagrada Familia in Barcelona, a building started in 1883 and still unfinished.

The works of these two personalities, together with those of the great Severini - for whom the Istituto Statale d'Arte per il Mosaico (State-Owned Mosaic Art School) in Ravenna is named - renewed interest in the art of mosaics in the XX century.

Felice Nittolo