18.39 Pleasure of the Tamasika type causes delusion to the self at the beginning and the end of enjoyment. Here 'delusion' means the absence of knowledge about things as they are. Pleasure springing from sleep, sloth and error are the cause of it. Even at the time of experience, sleep etc., are the cause of delusion. It is clear how sleep causes delusion. 'Sloth' is indolence in sensory operations. When sensory activities are slow, dimness of knowledge results. 'Error' is heedlessness regarding what ought to be done. From this also occurs the dimness of knowledge. Thus, these two also cause delusion. Such pleasure is declared to be Tamasika. Therefore what is meant is this:  subduing Rajas and Tamas, the Sattva alone should be allowed to develop by the aspirant for relase.