You must always base on Ten Gods 十神. Look for the strength of resource for weak charts/output for strong charts.
Strong healthy with support - smart. Being heavily suppressed - lack of intelligence.
Without resource for weak charts/output for strong charts ≠ not equal stupid. Do not have resource for weak charts/output for strong charts only mean he is not that smart.You cannot say someone is stupid when he is without resource for weak charts/output for strong chart.
Lack of intelligence when resource for weak charts/output for strong charts being suppressed. How bad depends on how severe is the suppression.This can come from TaYun, years etc.
You cannot base on elements. Without or lack of water does not equal lack of intelligence.
Cheers.
