In plain words
Man's chief duty is to make this body, the boon God has granted, pure, fruitful, eternally true and free of stain, and to give it back to God, and so offer it to Him.
To let us live along such holy and fruitful paths, in the culture of Bhārata they gave Bhakti, the chief path, the chief place. People take Bhakti to mean simply doing pūjās, keeping vows, going to holy places and going to temples; such good deeds alone, they think, are the marks of Bhakti. All these are only the first steps to Bhakti; they do not deserve the name of Bhakti. That does not mean we need give them up. Practising them, rejoicing in them and sharing them with others, step by step we must enter this higher level, the very form of Bhakti. Bhakti means to worship God with pure Prema, without staining the mind through mere contact with the giving of fruits. To turn upon Paramātma a supreme Prema, free of the wish for fruit, … no stain through contact with the hope of reward, purely selfless: that alone is Bhakti. Prema that has arisen from some cause or other cannot be Bhakti. We must bring forth a Bhakti and Prema that have no cause. It is this we must make grow. Just as the river takes its natural course towards the sea, the creeper towards the tree and the stars towards the sky, so must man's natural Prema flow out upon Paramātma. It must flow towards Paramātma. It must not take an artificial form. Wherever it rises, the river itself bears hardships of many kinds to join the sea, and makes its journey there. That is the river's nature. The reason: for the river, the sea is its own home. So too, to turn the pure Prema that is in man towards Paramātma, with no wish for the fruit at all: that is true Bhakti.
To keep many fruits in mind, to keep certain wishes in mind, and to pray to Paramātma only to make them bear fruit: this cannot be true Bhakti. It takes the form of a Bhakti of the rajas and tamas guṇas alone. Great devotees such as Rāvaṇa, Kumbhakarṇa and Kaṃsa prayed to Paramātma through a bond of rajoguṇa and tamoguṇa alone, and won great powers. Because they put these boons of protection and fruits, prayed for in hope of reward, to use again for their own selfish ends, the sāttvic nature sinks to the bottom.