But this argument is as illusory as the ontological one, from which, indeed, it borrows its strength, and of which it shares the weakness. For why should we ever pause in the regressive study of the phenomena of the universe, of which we only observe the slow evolution through immeasurable time? How do we reach a fountain-head at all? We are not warranted in saying that because we cannot think out an endless regress of infinite antecedents, _therefore_ we must assume a first cause. For that assumption of the ἀρχὴ, of an uncaused cause, when we have wearied ourselves in mounting the steps of the ladder of finite agency, is to the speculative reason equally illicit as is its assumption while we are standing on the first round of the ladder. Why should we not assume it, step over to it at the first, if we may do so, or are compelled to do so, at the last? The argument starts from the concrete and works its way backward along the channel of the concrete, till it turns round, bolts up, takes wing, and 'suddenly scales the height.' The speculative reason at length essays to cross over the chasm between the long series of dependent sequences, and the original or uncreated cause; but it does so furtively. It crosses over by an unknown path to an unknown source, supposed to be necessary. But again, what light is cast by this ambitious regress on the nature of the fountain-head. How is the being we are supposed to have reached at length, the source of that series of effects which are supposed to have sprung from his creative fiat? If we experienced a difficulty in our regress in connecting the last link of the chain with the _causa causans_, we experience the same or a counter-difficulty in our descent, in connecting the first link of the chain with the creative energy. And how, it may be asked, do we connect that supreme cause with intelligence, or with personality? We have called the assumption of this ἀρχὴ a leap in the dark, and we ask how can we ever escape from the phenomenal series of effects which we perceive in nature, to the noumenal source of which we are in search? By the observation of what is or what has been, we merely ascend backwards in time, through the ever-changing forms of phenomenal energy (our effects being but developed causes, and our causes potential effects), but we never reach a noumenal source. That is reserved for the flight of the speculative reason vainly soaring into the empyrean, beyond the very atmosphere of thought.