It is frequently claimed that there is a great and profound secret hidden in Rosslyn Chapel, a secret that has so far remained tantalisingly elusive. But if there is a secret, what kind of secret is it? Is it the contents of the Templar preceptories, hastily removed from France immediately prior to the order’s arrest and imprisonment in October 1309? Or is it the lost gospels of Christ appropriated from beneath Solomon’s Temple by the Knights Templar during their lengthy sojourn in the Holy Lands?

Another school of thought argues that the Holy Grail itself lies hidden beneath the floor of this mediæval / Renaissance chapel. Yet others are sure that Rosslyn’s secret treasure is the Ark of the Covenant, and there are even those who hold that the mummified head of Christ (or alternatively John the Baptist) is hidden there.

So, is this supposed secret of a worldly or spiritual nature? The fact is that no one knows what, if any, treasure lies secreted far beneath this building, whose vaults are reputedly as deep as the chapel is tall. The best bet, however, is that rather than a physical treasure there is some kind of spiritual gnosis – a mystical truth or revelation – lying hidden in Rosslyn Chapel; but what it is, and whether it has any relevance in the 21st century, is the vexed question lying at the puzzle’s very core.

In this short article I shall speculate that the secret is indeed spiritual in nature, and that although its meaning, significance and focus might have altered over the intervening centuries, it may still prove possible to uncover.

Rosslyn Chapel is a small, sanctuary lying approximately five miles (8km) south of Edinburgh. The reasons for its construction are themselves still unclear, although there are plenty of theories (see FT167:50, 193:37, 200:41). What is certain is that it was built at the instigation of Sir William St Clair, the third and last Prince of Orkney, between 1440 and 1490. During its construction, St Clair employed the services of skilled masons from all over Europe, and although convention says that the building was only intended as a place for private family worship, even a cursory examination will change your mind.

While the symbolism inherent in the chapel’s sumptuous carvings and geometry may have been solely for the personal edification of St Clair and his family, this seems unlikely. Rather, the building was designed and left for posterity as a learning tool, a coded book constructed in the most durable medium available – stone. The connections between Rosslyn and the Knights Templar are inescapable; William St Clair is said to have been a Templar (long after the order’s official destruction), and approved every last detail of the building – nothing, we must conclude, is there by accident.

If Rosslyn’s supposed secret lies in arcane references to sacred geometry or the esoteric workings of certain secret societies, then it is difficult to see why this has any relevance now. On the other hand, if the carvings contain deliberately suppressed information that could prove disastrous to today’s established Churches, then the secret of Rosslyn may be more accessible and wonderful than one might imagine.

The building itself is redolent with history; even the name Rosslyn is perhaps significant. According to research conducted by Robert Lomas and Christopher Knight for The Hiram Key (1997), the word can be broken into its two syllables, 'Ros' and 'Lyn' which have their roots in the Gaelic:'Ros', meaning ancient knowledge and 'Lyn', meaning down the ages. It can therefore be argued that even the name of the place is telling us what it is: a library carved in stone ciphers; an attempt to impart arcane knowledge in something more durable than paper – knowledge available only to those with the intellect to decode it.

Arguably, the most mysterious aspect of the entire building is the group of enigmatic 'cubes' located in the ceiling of the Lady Chapel, or retro-choir, located at the east end of the chapel. These cubes, which number in the hundreds, are seen emerging from musical instruments played by angels situated at the top of pillars running along the length of the small retro-choir. The cubes rise in silent tribute to the heavens and each cube carries its own set of delicate carvings on all of the exposed faces. But what could these carvings mean?

It has been suggested (initially in research conducted by the late MI6 agent and hotelier Stephen Prior and more recently by composer Stuart Mitchell – see Frozen Music) that since they emerge from musical instruments, logically, they must represent musical notes – but how can these odd shapes and patterns have any relationship to modern musical notation (which was still evolving in the 15th century)? And why might St Clair have chosen to hide important information in the form of obscure, apparently abstract, lines on small sandstone cubes?

Could it have been that he wished to express his disapproval and contempt for the summary and draconian treatment visited upon the Knights Templar in 1309 by the Vatican at the behest of King Philip the Fair of France? It is almost certain that St Clair was sympathetic to the Templar cause and had strong views on their murderous suppression. Likewise, he was also probably aware of a curious and proscribed series of musical notes called 'The Devil's Chord' and its eerie effects (see The Devil's Tunes). If he intended to use this knowledge to express his dissatisfaction at the treatment of the Templars, how could he conceal it without attracting unwelcome attention?

The answer seems to have been in a form of a code consisting of stress patterns created using fine sand sprinkled on thin metal plates and 'played' by some type of bow. This is identical to the method employed by the German physicist Ernst Chladni, sometimes called the father of modern acoustics, when he originally produced his famous 'Chladni Patterns'. These patterns are now commonplace in physics labs, used to demonstrate the hidden properties of sound, only they are now generated by using rapidly oscillating modules. Did Sir William painstakingly create the patterns using the bow-and-sand method, transcribing each note revealed onto the stone cubes?

Could the answer to Rosslyn's enigmatic puzzle, the key to what might be hidden there, be music – in other words, sound and, therefore, frequency? And if it is, does it make reference to the infamous 'Devil's Chord'?

In the 12th century, the Catholic Church gave the musical interval of the augmented fourth – spanning three whole tones, for instance from C to F# – the rather sinister title of diabolus in musica – 'The Devil in Music', also known as 'The Devil's Interval’ or, as mentioned, 'The Devil's Chord'. It was banned throughout Christendom and this ban, by extension, covered all contemporary European music, both sacred and secular. One must ask why the Church imposed this measure; what possible justification might there have been for this extreme sanction?

While it may be that the interval was seen as musically ‘wrong’, producing what was felt as a dissonance, it has also been argued that the tritone, due to its frequency and harmonics, and if produced in the correct setting, could induce visions and altered states of consciousness in those present.

Was the Church, aware of this, clamping down on what may have been seen as an unsanctioned form of access to the ‘divine’? Such an effect would, after all, have been anathema to the Catholic Church, reducing its absolute control over every aspect of the lives of the population.

But if, in fact, this is the secret of the cubes, can these notes still be reproduced? The answer is almost certainly yes, but to do so we would have to examine how instruments were tuned in the late mediæval period; perhaps, more specifically, we would need to learn how middle-eastern musical instruments were tuned and reproduce this tuning. The Templars had formed a relationship with their Muslim foes based on mutual respect forged in battle. This being the case, it is likely, given the spiritual core of Templar philosophy, that they became privy to certain esoteric practices and customs of Islamic mystical groups and this would almost certainly include music.

Modern musical tunings are based on an 'equal temperament' system, which was not prevalent in mediæval times, and therefore any attempt at reproducing the musical notes carved in the stone patterns would have to take this into account.

The following fascinating piece of information comes from a fellow researcher, Bill Downie, who is, amongst other things, a musician. Bill applied the ancient, esoteric art of Gematria to a group of notes comprising one version of the Devil’s Chord and discovered the following. From the information available, Downie, who defines the Devil's Chord as the notes F#, C and A, examined the associated frequencies, (370, 523, and 880) and noticed that they are very close to the following numbers: 373, 515 & 888.

In gematria – the ancient Greek (and later Hebrew) practice of numerology – we find that 373 literally means 'word' in Greek, 515 means 'Jesus' and 888 means ‘Iesous’, which translates as Jesus in Greek. The slight variation in frequency would make little or no difference to how it was perceived by the human ear. However, it would be interesting to see the effects on an audience if each frequency were produced using electronic equipment to recreate the frequency of the individual notes comprising the Devil’s Chord and also substituting the numerical values of the words for a frequency. It is also likely that the effect, if any, would not be confined to Rosslyn Chapel but to any given contemporary church or cathedral. They were all very similar in design, the major difference being in size, and it is likely that the greater the internal volume, the greater the likelihood of producing a wide range of sympathetic resonant frequencies, therefore enhancing the effect.

There is one final detail to add to the puzzle: one of the cubes is missing and, according to the chapel management, its whereabouts are currently unknown.

Does this mean that, even if the carvings on the hundreds of other cubes were decoded and transcribed as music, with all the appropriate tunings, that the missing cube would prevent the completed work from being performed? If this is the case, then perhaps the final fragment of the answer is concealed in a small, engraved cube of stone, which in turn is the last key to a greater understanding.

It could be said that we are all creatures of frequency one way or another, and there is every likelihood that specific frequencies can and do interact with human consciousness at some level. Should this information be encoded in the Rosslyn 'cubes', then their secret had huge implications for the mediæval Catholic Church – implications that are still valid today.

It would be fascinating to decode the patterns and finally hear the music put there by the builders of Rosslyn, frozen in stone for centuries awaiting someone who could unlock it.