So tonight V and I watched part three of Brian Cox and his Forces of Nature.
These programmes have represented some of the most televisually and educationally stunning content I have ever come across, but not always in the most joined up of ways.
I've wondered whether the order was fixed when the scripts were submitted, because the first episode was the most coherent. If the series had kicked off with Monday's third installment, I think it might have struggled to pick up an audience.
In truth the second half was profound and quite gripping, but the earlier sections had been a bit nerdy and Cox's efforts to descibe complex chemistry always seems to involve him waving his arms around and contorting his fingers in apparent bloody-minded determination not to have to resort to anything so Open University as a diagram.
In the end the moth (and its accompanying flame) came good as the gelling agent or recurring motif, but not quite as successfully as the snowflake in episode one, and some of the beautiful National Geographic-style digressions seemed just that, slightly indulgent asides without the obvious payload of a serious point delivered unequivocally at the end of each sequence.
Smothering his habitual smirk, the Professor finished with the observation that our common ancestor, our maker even, is the planet itself. This powerful conclusion felt non-pithy and well earned, and was rather cheekily illustrated by a moth tiptoeing over what looks like a valuable early edition of Milton.
In fact the one time in the series Cox has resorted to a sort of diagram it muddied one of the profounder points he's just made in episode two: that the apparent forward motion of the fourth dimension of spacetime may just be an artifact of subjective experience. Or as he put it, 'all in our heads'. The diagram however showed the sun and the planets objectively moving through four dimensions without any reference to an observer.