Sukha (joy, bliss) indicated by Jupiter, the giver of the supreme bliss and duḥkha (sorrow) indicated by Saturn, the god of death and disease are the two sides of the coin. Sukha is the upward pull of the loka (heavens, seven realms of light) which causes the head to go upwards whereas duḥkha is the downward pull of the tala (underworlds, seven realms of darkness) which causes the head to go down in shame and pain. From the guṇa viewpoint, sukha is sattva guṇa whereas duḥkha is tamas guṇa. Rajas guṇa is neither and causes continuance in the same level with neither rise nor fall. Therefore it is the cause of rebirth, or return to the same plane of this worldly consciousness.
In this lesson we learn the basics of studying sukha and duḥkha in the chart. Now our question: when did you last remember god? Was is in joy (sukha) or sorrow (duḥkha)? How often do you remember god in sukha? Sukha is symbolised by the right hand while duḥkha is symbolised by the left hand. In joy when we follow a spiritual path, we can never go astray whereas when we do so in sorrow, it is possible that we may resort to desperate methods of propitiation including dark means. This is what Parāśara meant by the spiritual path. Ṣoḍaśāṁśa shows the vehicles, and manas is the vehicle of mantra, the spiritual path to the goals.
At this stage we will not be studying such deep spiritual connotations.