spoil the underlying melody and the composer's design: but are introduced at such moments and with such vivacity and charm that they give the music the greatest beauty and spirit" Bottrigari, Venice 1594 Along with the improvisation, many of these tutors discuss articulation. Francesco Rognoni in 1620 describes the tonguing as the most important part of producing "a good and beautiful effect in playing wind instruments, and principally the cornett" (which of course had a very similar role to the trombone). The treatises discuss the various strengths of consonants from "le" through "de" to "te". But the focus of the text is for playing rapid notes "similar to the gorgia of the human voice" with "soft and smooth" double tonguing ("lingua riversa") using "le re le re". This is opposed to using "te che te che", which is described as "harsh, barbarous and displeasing". The natural 'pairing' of notes these articulations provide is similar to the instructions for string players who are instructed to slur ("lireggiar") pairs of eighth notes with one bow stroke per quarter beat. Another integral part of the early music sound-world is the musical temperament. Music in the middle-ages favours intervals of the fourth and fifth, which is why Pythagorean tuning was used. The interval of a third was used as a clash until the Renaissance, when it became consonant in compositions, which went hand-in-hand with the widespread use of meantone temperament. During the 17th century, Well temperament began to become more and more popular as the range of keys increased. Temperament affects the colour of a composition, and therefore modern performances, typically employing equal temperament, may not be true representations of the composers' intentions. These old tunings are the result of the natural harmonic series of a brass instrument such as the sackbut. As the bell is smaller than a modern trombone, the harmonic series is closer to a perfect harmonic series, which is the basis for just tuning. Without adjusting the slide, the first to second harmonic is a perfect octave, second to third harmonic is a fifth slightly wider than equal temperament and fourth to fifth harmonic is a major third slightly narrower than in equal temperament. These adjusted intervals make chords ring and are the basis of meantone. In fact, Daniel Speer says "Once you have found a good C (third position), this is also the place you will find your F.”