Hi everyone! Could you help me to clarify the difference between houses and cusps?
I understand the sign from the lagna is how you percibe that house connotation; for example the 4th rasi from the lagna tell us how we see/feel our mum, but the sign where the 4th cusp will tell us how our mother really is? Have i understood it well? In this case, what about the dad? don't we look the 10th to see how we see and feel about our dad and the 9th to see how he is in fact? how we'd work the father's case?
And when we are analizing the ruler of X Bhava in the Y Bhava, in this case, are we considering cusps or the bhava from the lagna? or if you look both, which will be the difference? I don't see it clear. ????
Thank you so much 
Ernst has a couple of very good videos on bhavas (Jyotish Building Blocks) that you should check out. But my understanding is the 9th Bhava is your father as an individual. The 10th Bhava is your relationship to your father. Let's say your 4th Bhava cusp is your mother as an individual. You can use that to read about your mother as an individual. So the 5th cusp would be your mom's 2nd house. The 6th cusp would be your mom's 3rd house or siblings. That is why your maternal uncles or aunts are 6th house. Stepmother is also the 6th house because according to Ernst in the old days they consider the father's 2nd wife is like the mom's sister - LOL
tuyet
The 10th is the father. The 4th the mother, these two are opposite as they are in a relationship just as you and your 7th house. The 9th is often used in india as the father, but its really not, its the parents as a unit and the culture a person grows up under, which is defined largely by the parents. In traditiional india the bride would go live with the husband at the husband's parents house. As a result, the father's culture demonated and the father dominated, so the 9th was used for father. But its really not in the simple sense of father, for that its the 10th and 9th is the parents as a unit crearting the upbringing and culture to the kid, which is no longer 99 percent defined by the father.
The 7th from the 4th is the 10th - the mother's husband which is your father too... That would make sense
tuyet
Thank you very much 
And what about when we are analizing a chart? when we take a ruler of a house which has no cusp, what is actually ruling this planet?
Thanks!