Western scientists, in an attempt to locate the soul, did experiments by weighing an individual in the moment before death and the moment after death. With their viewpoint based in matter, they hoped to discover that upon death something with material mass departed from the body and it could be measured.
Spiritual seekers with experience of the spiritual element in their lives, recognise that the Spirit permeates all existence and that all Matter itself is a manifestation of Spirit.
The swan is said to be able to separate milk from water. The spiritual man, through introspection, is able to separate the Spirit from Matter, Life and Mind through identification of its characteristic influence on existence.
Sri Aurobindo, in The Life Divine, discusses the soul element in man: “In the animal mind is not quite distinct from its own life-matrix and life-matter; its movements are so involved in the life-movements that it cannot detach itself from them, cannot stand separate and observe them; but in man mind has become separate, he can become aware of his mental operations as distinct from his life-operations, his thought and will can disengage themselves from his sensations and impulses, desires and emotional reactions, can become detached from them, observe and control them, sanction or cancel their functioning: he does not as yet know the secrets of his being well enough to be aware of himself decisively and with certitude as a mental being in a life and body, but he has that impression and can take inwardly that position. So too at first soul in man does not appear as something quite distinct from mind and from mentalised life; its movements are involved in the mind-movements, its operations seem to be mental and emotional activities; the mental human being is not aware of a soul in him standing back from the mind and life and body, detaching itself, seeing and controlling and moulding their action and formation but, as the inner evolution proceeds, this is precisely what can, must and does happen, — it is the long-delayed but inevitable next step in our evolutionary destiny. There can be a decisive emergence in which the being separates itself from thought and sees itself in an inner silence as the spirit in mind, or separates itself from the life movements, desires, sensations, kinetic impulses and is aware of itself as the spirit supporting life, or separates itself from the body sense and knows itself as a spirit ensouling Matter: this is the discovery of ourselves as the Purusha, a mental being or a life-soul or a subtle self supporting the body.”