A common and erroneous assumption, evidenced here, is that the Councils of the Church spin doctrines out of thin air, as if they all got together for no reason at all, and rather than go home having done nothing, decided to invent a new doctrine for the hell of it, just to make life interesting.
The Councils of the Church can be found here.
The English expert in the field is Fr Norman P Tanner, and he has produced an excellent
little history.
To repeat: Councils are called only when error threatens the life and faith of the Church (for example Pope John XXIII's decision to call what became the Second Vatican Council in 1960s was met with a resounding 'why?').
The council documents:
1 — assert the faith it is believed;
2 — highlight the dangers/errors that threaten the faith;
3 — pronounce the original belief more emphatically so that the error can be seen more clearly and avoided.
The sometimes go on to call exegetes and theologians to make further inquiry into certain areas highlighted, for the benefit of the Church.
Thus, whilst the earliest councils make scant reference to the Holy Spirit, that's not because the Church didn't believe in the Holy Spirit, but because the Holy Spirit wasn't being disputed – the nature of Christ was the cause of the dispute.
Likewise, no Council has ever debated reincarnation, because it has never been an issue within the Church.
A point totally missed, is that it is
not necessary to convene a council to make an infallible definition of dogma.
In 1950 for example, the Church declared the Dogma of the Assumption, the belief that the Blessed Virgin was assumed, body and soul, into heaven. This belief dates at least to the fifth century, and in the liturgies of the Eastern Church, is even older (the Dormition).
It has never been the subject of Council deliberation because it has never been disputed. It was declared true on the following basis:
Since the universal Church, within which dwells the Spirit of Truth who infallibly directs it toward an ever more perfect knowledge of the revealed truths, has expressed its own belief many times over the course of the centuries, and since the bishops of the entire world are almost unanimously petitioning that the truth of the bodily Assumption of the Blessed Virgin Mary into heaven should be defined as a dogma of divine and Catholic faith — this truth which is based on:
1 the Sacred Writings,
2 which is thoroughly rooted in the minds of the faithful,
3 which has been approved in ecclesiastical worship from the most remote times,
4 which is completely in harmony with the other revealed truths,
5 and which has been expounded and explained magnificently in the work, the science, and the wisdom of the theologians
— we believe that the moment appointed in the plan of divine providence for the solemn proclamation of this outstanding privilege of the Virgin Mary has already arrived."
Munificentissimus Deus
(The belief in the Assumption was not being questioned, but as Pope Pius explained, he had certain reasons to believe its pronouncement was timely.)
Thomas