The greatest concerts, the ones that stay in your mind for years after you've seen them, are the ones that open up a new style of music to you. Tonight's concert,  Thomas Hampson singing German lieder in Saanen church in Gstaad, fell firmly into that category for me.

Before talking about Hampson and lieder, it's essential to give a mention his backing band: the Amsterdam Sinfonietta, led from the violin by Candida Thompson - because they produced an exceptional piece of string playing. They opened tonight's concert with Mendelssohn's String Symphony no. 10, showing their qualities from the very first notes, in which they achieved a degree of togetherness that you would normally associate only with chamber players. This is a medium to large string ensemble, yet they went through rapid shifts of pace and dynamics with all the players absolutely on the nail. There seems to be a growing number of young orchestras who are reinventing orchestral playing in this vein, with youth and vigour not found in more traditional ensembles - the Australian Chamber Orchestra and David Grimal's Les Dissonances spring first to my mind, as well as the Geneva Camerata seen here on the previous night - and the Amsterdam Sinfonietta placed themselves firmly in that category.

Hampson joined them to start with Brahms's Four Serious Songs, set to biblical texts - three from Ecclesiastes, and one from Corinthians (the famous one with "for now we see through a glass darkly" and "faith, hope and love, but the strongest of all is love"). Where Hampson impressed most was with the way in which he imparted the maximum emphasis to every syllable. So as he sang that man wird wieder zu Staub ("will turn to dust"), the word Staub was delivered with withering scorn, the phrase die unrecht unter der Sonne ("the injustices done under the sun") was infused with world-weariness, the word Tod ("death") was transformed utterly according to the horrors of death to the prosperous juxtaposed with the joy of death to the destitute. In the last song of the four, the mood changes from harangue to rapture as the singer contemplates the power of heavenly love: Hampson expressed that rapture beautifully both in voice and in operatic feel for bold gestures and facial expression. 

We were, of course, in the perfect environment to hear this music: Saanen Church, an early seventeenth century building with a marvellous acoustic and precisely the sort of building where you could imagine being harangued by biblical preaching. And Hampson starts with the advantage of an exceptional operatic voice: rich, smooth and with total control over notes at all parts of his range. But I'm quite sure that it was his attention to the word setting and the delivery of individual syllables that made this performance so special - a lesson both biblical and musical.

An orchestral interlude in the shape of Wolf's Italian Serenade allowed Hampson time to get his breath back, the Amsterdam Sinfonietta the chance to relax and play something totally self-indulgent and fun - all the while maintaining the verve and extraordinary togetherness that had characterised their Mendelssohn. Then, it was time for Hampson to return with a set of varied lieder from Schubert and Hugo Wolf (plus a light hearted encore in the shape of Mahler's Rhine Legend).

The set showed us a rich variety of texts and moods: I won't list everything, but I'll mention two extremes to demonstrate the breadth of the material. Early in the set was Schubert's Memnon, a lament of the fallen Trojan hero whose fate is to be exiled to the heavens to appear only briefly each morning - elegiac and soul-searching. At the opposite end of the spectrum was Wolf's Der Rattenfänger, a setting of a Goethe poem which prefigures Browning's Pied Piper of Hamelin: the rat-catcher of title brags about his ability to catch rats and weasels, retrieve a town's missing children and (in the last verse) to capture maidens to be his sweethearts. It's a glorious piece of musical braggartry, delivered by Hampson with relish.

I went into this concert with little knowledge of lieder. I came out an enthusiastic convert. That's more or less the highest accolade I can give an evening's music.