div class=ts-pagebutton class=gotoPage data-page=1Page 1button div class=ts-imageimg data-url=do-wedont-wewhat-do-weknowhtmlpage=1 data-page=1 class=ts-thumb lazyload alt=Page 1: Do we—dont we—what do we—know loading=lazy src=data:imagegifbase64iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAQAAADYv8WvAAAAD0lEQVR42mP8X8AwAgiABKBAv+vAXklAAAAAElFTkSuQmCC data-src=https:reader030vdocumentssitereader030viewer2022020223575067c01a28ab0f07acfb3bhtml5thumbnails1jpg width=140 height=200 divp© 1926 Nature Publishing Grouppdivdiv class=ts-pagebutton class=gotoPage data-page=2Page 2button div class=ts-imageimg data-url=do-wedont-wewhat-do-weknowhtmlpage=2 data-page=2 class=ts-thumb lazyload alt=Page 2: Do we—dont we—what do we—know loading=lazy src=data:imagegifbase64iVBORw0KGgoAAAANSUhEUgAAAAIAAAACCAQAAADYv8WvAAAAD0lEQVR42mP8X8AwAgiABKBAv+vAXklAAAAAElFTkSuQmCC data-src=https:reader030vdocumentssitereader030viewer2022020223575067c01a28ab0f07acfb3bhtml5thumbnails2jpg width=140 height=200 divp© 1926 Nature Publishing Grouppdiv