In plain words
Viṣṇu is the one who, by this pervasiveness, has entered this Nature through many ages. This is what they have likened to Nature in the Taittirīya Upaniṣad. Antar bahiś ca tat sarvaṃ vyāpya Nārāyaṇaḥ sthitaḥ. That is, this Viṣṇu is the one who is everywhere, inside and outside. So this too is the very form of Nature. The one who has pervaded everywhere has the form of Viṣṇu. Here there is no difference between Brahmā and Viṣṇu. Only the names are different; in form and nature the two are one and the same.
Gurur devo Maheśvaraḥ. Who is this Īśvara? He is the very embodiment of all splendour. Īśāvāsyam idaṃ jagat: the one who dwells in the whole world is Īśvara Himself. His splendours are the five elements. Space, air, fire, water, earth: Īśvara is the very form of these five elements. He is the embodiment of all splendour. So wherever we go, we cannot keep our life without these five elements. So, in short, Īśvara is the very form of Nature. Brahmā, Viṣṇu and Maheśvara, endowed with the guṇas sattva, rajas and tamas, are the visible forms of Nature itself.
For man, nobility and generosity are the chief lifelines. Satyaṃ vada dharmaṃ cara. These chief commands are as dear as life to every human being. By man is meant merely the form of body, senses, mind and Buddhi. Man is the very embodiment of Ānanda, the witness of all these. He himself is Sat, Cit and Ānanda. Every human being is the very embodiment of Saccidānanda. Then why does man not recognise this principle of Saccidānanda? Through his attachment and his possessiveness towards this body, man has gone on turning his mind outward and developing it outward. So, yielding to its influence, people have gone on forgetting their true nature. All the people of today yield only to the influences of Nature; they make no effort at all to recognise the nature that belongs to the Ātma. Such humanity today: we must experience Advaita, that is, the oneness that is not two. That is what we call harmony. What is this harmony? We imagine that people joining with one another, coming together with one another, is harmony. That is not true harmony. Nor is it even sameness of feeling. Harmony is the very oneness that lies within the many. In the many we must try to recognise the one. Here lie Bhāva-advaita, Kriyā-advaita and Padārtha-advaita. Only when we recognise these three will this divinity become clear to us.
Bhāva-advaita. This is a cloth. Without thread there can be no cloth. Without cotton there can be no thread. Cotton, thread and cloth, all three are one. For it, cotton is the material cause.