Spencer defines life as the continuous adjustment of internal relations to external relations and perfect life is made up of accurate correspondences.
Life is distinguished from death by one unfailing test — which is growth. We cannot conceive of growth without evolution or an unfolding. In the lower forms of life growth is only apparent in modifications of form, and these modifications must necessarily be accompanied by increased experience.
The expression used in evolutionary philosophy — "adaptation to environment" — carries with it this idea. The bird or insect which has lost the use of its wings from lack of necessity to use them may be assumed to have added to its experience, or the experience of its kind, the knowledge acquired as an earth-bound thing together with that which it obtained as a creature of the air.
Or, to take an illustration whose data will not extend over so wide an area as evolution. We see traits and capacities evolved by necessity in single individuals. For instance, a child or man becomes blind; by virtue of necessity he develops the power of distinguishing by the sense of touch things which could not be so recognized by one who sees with the eyes. Here he has added to his experience as a being with sight that of one who has developed an added power of perception. In these cases there is the continuous adjustment of the internal relations, or those which initiate and keep going the life impulse, to the external relations which supply the experiences through which and through which alone enlarged knowledge may come.
Seed alone cannot bring forth a harvest. In order to do so, the seed must give expression as a plant to the vital impulse locked up within it. The internal relations which not only give the impelling force to growth but determine the specific characteristics of type, variety and species must be continuously and harmoniously adjusted to the external relations of climate, soil and season. The correspondence must be a continuous and harmonious one. During the growth of the plant every effort of its entire existence, every force of its life impulse, is given up to the physical manifestation of itself as a plant in stem, branch, leaf and flower in turn and in strict harmonious sequence before the forces are turned inward to culminate as seed in the complete fruition of its life. The amount and quality of the seed so produced to give rise to future plants depends entirely and always upon the perfection of the physical manifestation — in other words, the external relations. If the gardener or some predatory animal or insect prevents the growth of branch and leaf, there can be no harvest or seed as the result of growth. The bare stalk remains as the only evidence of the vital impulses contained within the original seed. Also should the external manifestation of life show itself in excessive physical growth by virtue of faulty adjustment of external to internal relations there is an equally barren harvest, for all the life impulses have been dissipated in the production of that which perishes. Thus it is seen that without the perfect correspondence between the life impulse within and the material manifestation without, an equal balancing or harmonious adjustment of the internal to the external and vice versa. There can be no completion of the cycle by which alone existence can be measured.
Everything throughout the universe proceeds by virtue of absolute harmony. There can be no such thing as real isolation either internal or external. All forms of existence are interdependent.
Each planet has its own cycle, but could not maintain its course independent of the influence of all the other planets any more than it could apart from the influence of the sun itself. The absurdity of any planet attempting to start a cycle alone, even under the influence of the central sun, is manifest.
In man we see the action of the same immutable unswerving law. In his physical structure we find each cell has its own distinct functions in building up colonies of cells — each colony has its own work in maintaining the integrity of the separate physical functions of the body. The body could not grow or even maintain vitality if these relations should become inharmonious. Nature is always striving to restore perfect adjustment where any fault exists; she makes the attempt to throw off any cell or colony of cells which is out of harmony with the whole. Failing in this, the result is disease, decay and death. This universal law of harmonious adjustment applied to the external physical or evident relations must be equally applicable to the internal or causative and real relations, and becomes therefore a necessity for either growth or change, in other words, for life itself.
This necessity for harmonious adjustment of the internal relations to each other, of the external relations to each other and of the internal to the external being true in all forms of existence whether vegetable or animal life or the forces of the solar system, how much more necessary must it be to the race as applied to the relations between man and man. To say that we can live apart from and independent of each other is not only going in opposition to every law of nature but is a crime against our brother. Harmony is perfect law. Discord or lack of harmony is crime. Any attempt of the individual, whether that individual be the cell, man, or planet, either in the physical or spiritual aspect to maintain its individuality regardless of the whole of which it is a part, or to express itself as a unit under the idea that it is or can become a law unto itself must bring upon itself the same penalty which attends a like effort on the part of the cell in the physical body. "To live to benefit mankind is the first step," says the Voice of the Silence.
"Do not fancy you can stand aside from the bad man or the foolish man. They are yourself though in a less degree than your friend or your master. But if you allow the idea of separateness from any evil thing or person to grow up within you, by so doing you create Karma which will bind you to that thing or person till your soul recognizes that it cannot be isolated. Remember that the sin and shame of the world are your sin and shame; for you are a part of it; your Karma is inextricably interwoven with the great Karma." — Light on the Path