“THERE is a lot to be pessimistic about.” What better way to hook in a Radio 4 audience than the promise of misery? And Professor Margaret MacMillan knows her audience. As she and her chair, Anita Anand, introduced the first of her Reith Lectures (Radio 4, Tuesday of last week), we heard how the world could be just “one tweet away from Armageddon”.

Professor MacMillan is a historian of warfare, and her series “The Mark of Cain” asks whether war can be considered to be an absence of peace, or whether societies are naturally predisposed to pursue organised violence. Warfare requires a great deal of organisation; or, put it another way, groups of people who are organised enough to form something like a society will deem the pursuit of warfare as an appropriate expression of their cohesion.

All of this sounds suitably depressing, except that there are, Professor MacMillan argues, many positive benefits to war: technological advance, education, and even greater democracy.

This brings us round neatly to the NHS, one of the cheerier outcomes of the Second World War. As public services, free at the point of delivery, the NHS and the BBC share much ideological DNA; as well as the same challenges of budget and political hectoring. So it was fitting that Between the Ears (Radio 3, Saturday) should feature a tribute, the NHS Symphony, whose modest scale and careful use of resources gave nobody the impression that vast sums of public money were being wasted.

In another country, in another age, one could imagine a vast cantata, populated by full symphony orchestra and chorus, blasting forth a paean to communitarian values. The NHS Symphony had merely a piano to accompany the chorus, and a score whose wordless vocalisations markedly avoided any statement whatsoever.

Instead of a libretto, there were the soundscapes of two hospitals in Birmingham where dramas large and small unfolded. A hospital is filled with its own music — the beeps of machinery, the chirrup of desk telephones — and, alongside this, we heard the gentle undertones of conversation, sometimes forming a coherent storyline, more often merely the clichéd patter of hospital talk.

From musica humana to musica universalis, and the interval that unlocks it: in The Listening Service (Radio 3, Sunday), Tom Service celebrated the perfect fifth: that combination of pitches by which the cosmos is assembled. The medievals knew it: the fifth is the interval sounded by the motion of planetary bodies, a sound represented by the drone that underpins spiritual chant.

There is something wonderfully old-fashioned about The Listening Service, a programme unashamedly pedagogical, overflowing with enthusiasm for music, wherever it comes from, and even featuring a segment on how to build your own monochord: the Blue Peter for classical music. I await with baited breath programmes devoted to the dominant seventh, the augmented sixth, and the Neapolitan cadence.