276 TRANSACTIONS OF THE PLYMOUTH INSTITUTION. 
would be those of units whose characteristic was perceptive 
activity more or less clear. The beginning of what we ordinarily 
call Life would be the emergence of the first and simplest aggre- 
gation of units endowed with more perceptive activity than others 
that had previously been aggregated ; or the first combination, 
into simplest coordination, of the smallest number of units requisite 
to form a distinctly sensitive system. 
The speculation of Leibnitz may be left as food for speculative 
intellects ; though I believe it to embody some profound philo- 
sophic conceptions. 
There is only one other solution tentatively put forward in 
modern times to which I need refer; it is that worked out in 
such an interesting way by Professors Stewart and Tait in their 
combined production, entitled The Unseen Universe, Holding 
rigidly to the principle of Continuity in its utmost logical applica- 
tion ; recognizing in organic structures the working of physical 
and chemical laws as surely and comprehensively as in the inorganic, 
they first of all reason up from the admitted data of physical 
science to the existence of an unseen universe, of which the 
present visible universe is the evolved outcome — believing that to 
be the true logic of scientific knowledge. The visible universe 
expresses, and is the form of, the energy that was in its antecedent 
Unseen Universe, but not all that was in the Unseen. In the 
Unseen Universe there was one form of energy which found its 
outlet in what we now know as the material visible system ; and 
there was another " agency " which did not so find an outlet. 
This latter something is Life ; and as the visible material world, 
and all that physically enters into organisms, as mere material 
structures, are the outcome of the one form of energy, so Life in 
organisms, regarded as the mysterious strategist that seems to 
direct and regulate all in an organism, is the outcome of that 
other form of energy — the Life in the unseen. All things alike 
are originally from the Absolute along a line of vast recession ; 
but one line of things — the material, the visible — comes from the 
Absolute by means of an unseen intermediary operating in the 
unseen; and the other line of things — the living — comes from 
the Absolute by means of an unseen intermediary operating, also, 
in the unseen, and designated Life. Thus, just as now, Life only 
comes from Life, so, in the first appearance of Life on the globe, 
it came from the Life in and of the unseen. Thus the principle 
