To the Museo Nacional de Arte de Catalunya (MNAC to its friends) to see the newly re-opened and re-modelled section on Catalan Romanesque. Most impressive – cool, clear galleries with a reduced number of exhibits, better displayed. Since a major element of the Catalan Romanesque was a highly developed tradition of church murals, there are some wonderful reconstructions of interiors, with the actual frescoes presented as they were located in their now ruined and collapsing original sites. There's an absorbing video about how you transfer a plaster-based fresco from a crumbling wall to a secure museum – which you would think is a task at the impossible end of tricky.

These works of art were, of course, visual aids for religious education. One of the most striking exhibits is a 3D projection (you have to put on special glasses) of the church porch at Ripoll – which presents some 30-odd vignettes, depicting key stories from the Bible. These are stone bas-reliefs, arranged in rows like a cartoon strip on each side of the round arch of the main door of the church. It's a kind of medieval Wikipedia – if you were illiterate (and most people, from peasants to nobles, were), you could look at the porch and access information about all the important stories on which your faith was based.

Wandering around, my attention was caught by a panel showing the martyrdom of Saint Julitta – see the detail above. Now, there is a family connection – my wife is called Julita, so the blessed Santa Julitta is her patron saint - but mainly I found the image (to be perfectly frank) fascinatingly entertaining.

Apart from anything else, the good lady seems to have been martyred not once, but four times – by saw, by nails, by cauldron, and lastly and most conventionally, by the sword. This is not usual, and the phrase 'glutton for punishment' comes to mind. Not to mention 'difficult', since it must have been hard to maintain religious enthusiasm ... or consciousness ... or breath ... after first being sawn in half. In Martyrdom #2, Julitta is shown having nails banged into various parts of her head and abdomen, while continuing to frown with religious ecstasy (or possibly worrying about where she left the aspirins). The next image shows Julitta and her son Saint Quiricus (family tradition, you know) simmering in a large cauldron, being stirred vigorously. And finally, exasperated, the Bad Guys resort to the good old reliable sword. In each of the four images, I note, Julitta is wearing a different elegant outfit – which might suggest some serious prior shopping (“I haven't got a thing to wear ...”).

Why on earth did the … matyrisers? martireros in Spanish? anyway, the guys doing the martyring ... use such unconventional methods? It smacks of improvisation, of DIY, don't you think – rummaging around the kitchen to see if there was anything handy. (“Here's an egg-whisk – any good?” “Nah, too much like hard work...”)

But I'm reading this image as a sceptical post-Postmodernist, saturated with the full range of modern culture, which is absolutely not the same mindset as that of the painter or the audience in the 12th Century. The stylised simplicity of the drawing looks to me like caricature, like a quirky cartoon strip. The 12C Catalan would not even notice the style, would see through it directly to what it signified – extreme violence against the sacred, and would very probably have personal experience of the crude realities of physical assault which would illuminate the image.

Anyway, brutality is eternal. In the Ruandan genocide, people did indeed rummage around the kitchen, grab the sharpest thing they could find, and set off to kill their neighbours. And that's not funny at all.