As a Renaissance specialist I have always put Josquin at the centre of my musical world. To have the opportunity to perform any of his music is the greatest privilege, but his masses represent something apart. In them he worked out – and perfected – his response to a particular compositional problem: how to set the words of the five movements of the Mass Ordinary, rather as Beethoven explored the possibilities in the traditional movements of a symphony. Mass setting was central to all the composers of the Renaissance period, and Josquin was determined to outshine everybody. He did this by repeatedly coming back to the challenge – his masses come from every period of his career - and by restricting himself more or less entirely to four voices, to concentrate his technique. In these masses the greatest composer of his age audibly matured.

I chose to record all Josquin's masses partly because the Tallis Scholars have been associated with his music for their entire career; partly because his masses make the best possible recording project; and partly because 2021 will mark the 500th anniversary of his death. Nineteen masses over nine discs is substantial but manageable, whereas 107 by Palestrina is not. And they represent something of an ultimate challenge both intellectually and technically to any group of singers that wants to perform Renaissance polyphony. The intellect is challenged by the often mathematically-based writing – canons, augmentation, inversion and so on; the technique by the unusually wide vocal ranges and unexpected stylistic twists and turns, which were the result of a composer experimenting over 40 years. Yet every Mass has its own individual sound world. And in that lay the excitement of recording them all.

A few of these settings have become well-known in recent times. The Missa Pange lingua is a name many people have heard; the Missa L’homme armé sexti toni is famous for its mesmerising last movement. Some were the most celebrated settings in Josquin’s own time – the Missa De beata virgine survives in 54 contemporary sources, surely a record. I thought that in the Missa Ave maris stella I had found a setting that could become part of the standard cathedral repertoire in the way Byrd’s four-part Mass has become – until I saw the voice ranges. We quickly had to acknowledge that Josquin had different parameters from ours. How we would manage them would be the main challenge for myself and the Tallis Scholars over the 30 years and more we will take to make this set.

The year 2021 offered us as a convenient deadline for this project. I hope Josquin’s 500th will be celebrated as fully as similar anniversaries by later composers, and I hope other groups will release complete recordings of his motets and secular music to fuel the fire. The Tallis Scholars intend to sing all his Masses in a planned series of performances throughout the world in that year.

I deliberately included in my set as many ‘Josquin’ masses as has ever been allowed – including the apparently spurious Missa Da Pacem, now thought to be by Noel Bauldewyn, but not long ago paraded as the quintessential Josquin mass – specifically in order to show what these compositions actually sound like, rather than what they look like on the page. There is good reason for thinking that they are all by him, despite scholarly misgivings, not least because they were published as genuine in Josquin’s lifetime. Anyway, surely we should allow a composer of genius the luxury of changing his style and method, not just as the years go by, but between coeval pieces. Our set will be completed by 2020; the latest disc to be released – the sixth of the eventual nine, containing the Missa Di dadi and the Missa Une musque de Biscaye - will is released today (October 28). It is a pleasure to be able to offer to all lovers of polyphony the most complete evidence yet of the genius of one of the world’s greatest composers.

Peter Phillips's latest recording with the Tallis Scholars features Josquin's Missa Di dadi (Mass of the Dice) and is out now. Order from Amazon, iTunes or Presto.