Comprehension means knowing what is so but not why it is so; realization means knowing both what is so and why it is so.
The trouble with comprehension is that, once one knows what is so, one assumes one has reached the ultimate truth, making it difficult to seek why it is so. Even if one attempts to understand why it is so, insufficient meditative concentration combined with conceit prevents one from truly knowing why it is so. Transitioning from comprehension to realization is exceedingly difficult. However, what ordinary people refer to as "comprehension" merely signifies understanding some Buddhist theories; it is far from knowing what is so, for they remain unaware of the ultimate aim of the Dharma and are still distant from true comprehension.
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