The majority of El Greco's work is to be found within Spain, and it was within this country that the Greek painter would peak as an artist, having earlier lived for many years in Italy. Religious themes and figures dominate the artist's oeuvre, and this highly religious man would court major religious institutions in order to acquire some highly impressive commissions. His artistic style was unique and expressive, and those who favoured it would become strong supporters of his work. When viewing Saint Peter and Saint Paul we can immediately appreciate the light tones that he used, with a glowing reflection coming from the various elements of drapery. He simplifies both saint's clothing into tones of green, brown and a pinkish red. Their figures fill most of the scene, with just a little room open at the top for a El Greco-esque sky to float by. The hallmarks of his work are all here, present and correct, with dark and light tones placed next to each other for a striking finish. The saints hold each other delicately, whilst staring directly at the viewer.
This piece is not one of the artist's biggest pieces, at just over a metre tall, and just under a metre wide. Clearly, El Greco planned the composition in his mind first and realised that there would not be huge levels of detail within this commissioned piece, and therefore decided to slightly reduce the size of the canvas. Of course, he used oils for the entire piece, as he did throughout his career. For several centuries tempera had been used instead in parts of southern Europe before the influence of northern regions brought about a general preference for oils instead. El Greco learnt much of his trade in Italy, and so would have been well briefed on the Renaissance work from previous centuries. He also was influenced by Titian significantly and both artists favoured brighter tones than was normal for their respective periods. One noticeable aspect of Saint Peter and Saint Paul is how long the hands are, giving an example of how the artist elongated his figures in the latter part of his career.
The alternative versions created by El Greco include one in Stockholm from between 1605 and 1608 and also another in St Petersburg from 1587-1592. Those two are based indoors and are near-identical, whilst the version in Barcelona, which came in the middle of them, can be considered the best of all. Its brighter tones are simply more accurate to the trademark qualities of the artist, and explain much more clearly how this artist became an inspiration for later artists from the Expressionist movement. The other versions are technically impressive, but slightly more subtle, even sombre, in atmosphere. Saints Peter and Paul were two of the Apostles of Jesus and you might notice how the clouds in the sky are carefully manipulated so as to give the impression of halos around their respective heads. Experts have suggested that the bright tones was specifically influenced by the artist's knowledge of Venetian art. One can see similar in other titles such as Tears of St Peter, Opening of the Fifth Seal and St Peter in Penitence.