Many years ago, I taught a course at the University of Aberdeen on the ‘4As’ of anthropology, archaeology, art and architecture (Ingold 2013). As we had been discussing flint-knapping, I invited the master-knapper, John Lord, to give a demonstration. We watched in awe as he skilfully detached flakes from a flint nodule of irregular shape to reveal the classical, bifacial form of an Acheulean handaxe. Then it was our turn to use wooden or antler hammers to detach flakes from fragments of flint. After an hour or two, none of us had made any headway. What looked simple in practised hands would have required years to learn, not a single afternoon! Nevertheless, the workshop taught us an important lesson. As Bentley and O'Brien (2024) remind us, mastering the skills to make an Acheulean biface requires hundreds of hours of practice. The question is, why does it need so long? What is going on during these many hours?

多年前，我在阿伯丁大学教授了一门关于人类学、考古学、艺术和建筑的“4A”的课程（Ingold 2013）。当我们一直在讨论打燧石时，我邀请了打砧大师约翰·洛德 （John Lord） 来做一个演示。我们敬畏地看着他巧妙地从形状不规则的燧石结节上分离出薄片，露出 Acheulean 手斧的经典双面形式。然后轮到我们使用木锤或鹿角锤从燧石碎片上分离薄片。一两个小时后，我们谁也没有取得任何进展。在老练的手里看起来简单的东西需要几年的时间来学习，而不是一个下午！尽管如此，研讨会还是给我们上了重要的一课。正如 Bentley 和 O'Brien （2024） 提醒我们的那样，掌握制作 Acheulean 双面的技能需要数百小时的练习。问题是，为什么需要这么长时间？在这许多小时里发生了什么？