This consideration accounts for a feature of the purgatorial discipline which at first sight would appear quite contrary to the Montessori spirit. On the lower slopes of the Mountain, below the gate of Purgatory proper, the souls whom Dante meets are grouped informally, or encountered individually; but within the gate, on each of the seven terraces where the seven capital sins are successively purged, the souls are engaged in groups on the same task, or similar ones. How is this consistent with free, spontaneous, individual development? Is not this simultaneous occupation at the same lesson more like a Froebel class, or even an old-fashioned Public School form than a Montessori group? The answer, surely, is in the negative. Collective work has indeed its permanent value, and simultaneous movements at intervals, their ample justification. In the _Purgatorio_, as in the Montessori School, the class-system in its extreme and rigid form has been superseded; though scope is given, in certain ways (as in the _revised_ Montessori scheme), for the expression of the social instinct.[209] When the pupil is inwardly fit for a move, he “feels it in his bones”; and then—and not till then—he moves. The task in which he is engaged in company with his fellows holds him just so long as it is needful and appropriate to his own case: the moment of its beginning and that of its ending are entirely independent of the doings of his fellow-learners. Once more, the Terrace of Purgatory resembles a Montessori group rather than a Kindergarten class in its freedom from obvious direction. There is no attractive, central, dominating figure, like the Froebelian teacher, on whom all eyes are fixed in the spirit of Psalm cxxiii, _Ad te levavi oculos meos._ The grouping of the learners is apparently spontaneous, and different groups are sometimes engaged simultaneously on different tasks. Again, the School of Purgatory is essentially modern in its emphasis on “expression work,” and its abundant supply of “didactic material.”