This should not be forgotten, now, when returning from the mysteries of metaphysical celebrations.
At first sight, this mode of thinking seems to us very luminous, because it is that of so-called sound commonsense. Only sound commonsense, respectable fellow that he is, in the homely realm of his own four walls, has very wonderful adventures directly he ventures out into the wide world of research. And the metaphysical mode of thought, justifiable and necessary as it is in a number of domains whose extent varies according to the nature of the particular object of investigation, sooner or later reaches a limit, beyond which it becomes one-sided, restricted, abstract, lost in insoluble contradictions. In the contemplation of individual things, it forgets the connection between them; in the contemplation of their existence, it forgets the beginning and end of that existence; of their repose, it forgets their motion. It cannot see the woods for the trees.
From: Frederick Engels, 1880: Socialism: Utopian and Scientific.