 The laws of stratification can be summed up in four key terms: recurrence, modification, novelty, and distance. Some lower categories recur in higher strata as partial aspects of higher categories, and every recurring category is modified in its recurrence. Whenever a lower element is taken into the higher it is affected by its new place in relation to others in the new stratum. These two principles constitute a vertical interconnectedness of the strata. While the categories of causality and substance, for example, appear to us initially in discussion of physical things, they recur modified in the domain of the organic. Because categories are not simples but complexes of factors, some of those factors may remain stable while others are modified, constituting the recurrence of the same but non-identical category. These recurrences have to be shown in each case, and one of the tasks of categorial analysis is tracing the modifications of a single category throughout the strata. Next, every stratum contains is own unique and novel categories that are not present in the lower stratum, nor are they a sum of them. Finally, recurrence, modification, and novelty imply that there is not a continuous series of levels, but gaps or incisions between them. The last two laws of novelty and distance are what give the impression of the ontological irreducibility of the strata (A50b). For instance, while the category of metabolism in the organic may necessarily incorporate some aspects of linear causal process, it is itself a distinctive kind of process that is irreducible to them. Thus, recurrence and novelty respectively reflect the aspects of continuity and discontinuity among the strata. Categorial novelty inserts an incision or cut into the apparent continuum of categories, creating a distance or gap between strata. The laws of dependence can also be summed up in four terms: strength, indifference, matter, and freedom. The “fundamental categorial law” of strength says that the lower categories on which higher strata depend are conditions or fundaments, while the higher are weaker. The lower are indifferent to whether anything higher builds on them or not, since their vocation is not to serve the higher. As “matter,” the lower categories, if incorporated into higher levels, constrain what the higher may do with them but do not determine it. Lastly, the higher always has leeway despite its weakness and dependence on the lower (A55d). Laws of dependence help to characterize superposition relations. They organize the order of the strata, so that the spiritual level is founded on the psychological level, which in its turn is founded on the biological one. Conversely, the biological level is the bearer of the psychological level and the latter is the bearer of the spiritual level.