Excerpts from the original CD booklet:

Sonata a Preghiera sulla Quarta Corda
The term "sonata" is often to be found in the titles of Paganini’s works - the Sonata Napoléon, the Sonata Varsavia, the Sonata Sentimentale. In this instance the term means "piece to be played" as opposed to "cantata" which refers to a work which is to be sung.
Paganini based his "Variations" on the famous air by Rossini "Dal tuo Stallato Soglio" which has delighted audiences ever since its first appearance. The orchestral arrangement has been handed down to us but not the violin score. We know that a signed such score was produced but its whereabouts are now unknown. This, however, should not surprise us. Like many other virtuousi Paganini was reluctant to distribute the violin parts because he was afraid that they might be copied. There are three variations. The use of the "sul ponticello" notes with their characteristic nasal features is rather curious. They add a surprising element to those sounds which have already been heard. The "finale" is also worthy of special notice.

I Palpiti
Following precedent, it was Rossini’s theatrical work which inspired these variations. Here Paganini is drawing upon the theme "Di tanti palpiti, di tante pene" from the heroic melodrama "Tancredi". Perhaps written in 1819 (the work by Rossini had been performed at the Teatro La Fenice in Venice in 1813), this piece however only came to be played in public in 1828. In this work we encounter those typical features of Paganini’s compositions which enabled him to achieve heights of the greatest quality without abandoning advanced levels of lyricism. There is also an extant version of this piece with a harp accompaniment which was written by Paganini himself.

Non piu Mesta Accanto al Fuoco
A reliance upon opera themes is one of the characteristics of Paganini the composer who with time became ever more sensitive to the need to provide a "performance". His friend Rossini gave him the opportunity to follow this path. The talent of Paganini lies in his abilty to transpose musical forms from another source onto the strings of a violin without diminishing their original strength and effectiveness. "Non più mesta" is a work which is written with very great care and which concludes with great musical virtuosity. It is based upon a famous part from the light opera "Cenerentola ovvero la bonta in trionfo" which was first performed at the Teatro Valle in Rome in 1817. The piece employs the usual Paganini "scordatura" of a semitone for the violin part, an element which is also found in the previous works. The score for the second violin has not remained to us. This signed piece is said to have been given to the Count di Cessole e di Massa. We know about its existence because of what is written on one of the orchestral scores. This piece is made up of four variations and the last - which is clearly transcendental is tone - involves evocative echo effects.

Nel Cor piu non mi Sento
Airs by Paisiello were employed by Paganini in a number of his own compositions: one for a solo guitar, two for a solo violin (one of which was published only recently), and one for violin with violin and cello accompaniment (the manuscript of which is kept in the British Library in London).
These variations are based upon Guhr’s transcriptions which are certainly very faithful to the original because as the director of the Frankfurt Orchestra this musician often had the opportunity to meet Paganini, to listen to his playing, and to analyse his techniques. As a result, he is a more than reliable authority. These variations constitute a further expression of Paganini’s playing technique which here undergoes a sort of super-explosion of quality. We thus encounter trills plucked by the left hand, chromatic sequences effected by wide bow movements, and arpeggios. They represent a break with works dedicated exclusively to the fourth string and they use all four strings to achieve a height which involves an expression of the impossible.

I Capricci
This piece is radically different from the others and Paganini classified it as his "Opera I". He himself dedicated it to "artists", that is to say to those professional musicians of a sufficient technical ability to overcome the difficulties it presents. The "Capricci" are the result of a critical reassessment of how to play the violin and the outcome of new forms of virtuosity. They are veritable "studies" in which the violinist performs everything of which the instrument is capable in an exceptional creative synthesis. The violinist achieves a fusion between the cadences of concert playing and the features of private study. The "Capricci" thus represent the first "transcendental" image, the outcome of experiences achieved through contact with an audience which listens to what is played and accepts the performance without raising doubts or questions.
The work itself includes twenty-four pieces divided into three parts and was certainly finished by 1817. Giovanni Ricordi catalogued this work in January 1818 and publication took place in June 1820.
In this work by Paganini we find a recurrent element which is also to be found in Domenico Scarlatti’s "esercizi per gravicembalao" (see CDC 006 P&P 1996). This element is the "sonata antica" which has a single principal theme. It involves the exposition of that theme; modulation of the tone of the dominant or the relative if the beginning is in the minor key; then a somewhat broad development and various changes in tonality; and finally a new presentation of the theme and a return to the fundamental tone. "Capricci" numbers 4 and 19, however, unfold in a different way.
The "Capriccio n.2 in B minor" is characterised by constant ups and downs by the right hand and broad extension of the left hand. The chromatic excursions are very long and markedly difficult. The two base voices, one constant in form and the other involving a melodic movement, give life to the tecnical motif which is achieved with jumps over the strings (and more specifically using the first, third and fourth) and a bow which is always light and elastic in its employment.
In the "Capriccio n.14 in E flat major" it seems that Paganini’s violin is engaged in an attempt to replace the whole orchestra and it is certainly successful in this endeavour. This piece has a progressive evolution: a chord, two chords, three chords together, a re-expression on the keyboard, then four chords together, and all this moving from piano to fortissimo. The title which some people have used to describe this piece, "la marcia", is inappropriate - there is nothing of the spirit of a march to be found in its character.
A very fine contrast is one of the main features of "Capriccio n. 21 in A major". The beginning of this piece - amoroso "con espressione", something which is more than natural to an aria from an opera - involves a melody which advances on two chords in a way which suggests that it wants to bring together two different vocal registers without, however, abandoning light instrumental flights. In a way which is typical of Paganini, the "presto" then suddenly emerges and we encounter an explosion of rapid plucked scales and arpeggios of great intensity.