How should I take the concept of the following sentence?

In this following context, how should I take the bold and italic sentence? Should I take it as: 'it is no longer known more important than all.'? Should I take its concept meaning as: 'the matter is known nothing rather than all changing.'? Context: > Till recently scientists believed in an indivisible and indestructible > atom. “For sufficient reasons physicists have reduced this atom to a > series of events. For equally good reasons psychologists find that > mind has not the identity of a single continuing thing but is a series > of occurrences bound together by certain intimate relations. The > question of immortality, therefore, has become the question whether > these intimate relations exist between occurrences connected with a > living body and other occurrences which take place after that body is > dead.” > > As C. E. M. Joad says in The Meaning of Life, “matter has since > disintegrated under our very eyes. It is no longer solid; it is no > longer enduring; it is no longer determined by compulsive causal laws; > ***and more important than all, it is no longer known.*** The so-called atoms, it seems, are both ‘divisible and destructible.” The > electrons and protons that compose atoms ‘can meet and annihilate one > another while their persistence, such as it is, is rather that of a > wave lacking fixed boundaries, and in process of continual change both > as regards shape and position than that of a thing.” Source: P. 59 Buddhism in a Nutshell by Narada Thera