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+# CORPUS-0004
+## Cost Includes More Than Purchase Price
+### Status: Training Corpus Seed
+### Layer: Layer_0--Primitive_Facts
+### Purpose: Teach that the cost of a venture includes every expense required to acquire, hold, move, protect, and sell the good
+### Repository Path: docs/training/corpus/Layer_0--Primitive_Facts/CORPUS-0004-cost-includes-more-than-purchase-price.md
+
+---
+
+## 0. Principle
+
+Purchase price is not total cost.
+
+A trader who buys a good must also consider the cost of making that good available for sale in another place or time.
+
+Total cost may include:
+
+- purchase price
+- porterage
+- cart hire
+- animal feed
+- storage
+- dues
+- losses from damage
+- delay
+- spoilage
+- guards or escorts
+- payments to clerks, witnesses, or handlers
+
+A low purchase price may still produce a bad venture if the remaining costs are high.
+
+---
+
+## 1. Roman-Visible Example
+
+A trader buys oil in Ostia for 10 asses.
+
+He plans to sell it in Capua.
+
+The purchase price is only the first cost.
+
+He may also pay:
+
+- 1 as to move the amphora from seller to storage
+- 2 asses for storage before departure
+- 4 asses toward cart space
+- 1 as for handling at arrival
+- 1 as lost through leakage or breakage risk
+
+The oil did not cost him 10 asses.
+
+It cost him 19 asses before he could sell it.
+
+---
+
+## 2. Minimal Cost Structure
+
+A venture cost requires at least:
+
+1. acquisition cost
+2. movement cost
+3. holding cost
+4. transaction cost
+5. loss or damage risk
+6. time cost
+7. opportunity cost
+
+A trader must count all costs that exist because the venture exists.
+
+---
+
+## 3. Incorrect Modern Assumption
+
+Incorrect assumption:
+
+> If a trader buys for 10 asses and sells for 14 asses, he earns 4 asses.
+
+Correction:
+
+> He earns 4 asses only if there are no other costs. If movement, storage, dues, or damage cost more than 4 asses, the venture loses money.
+
+---
+
+## 4. Simulation Use
+
+This principle supports:
+
+- venture accounting
+- transport cost
+- storage cost
+- spoilage and breakage
+- taxes and dues
+- delay penalties
+- comparison between possible ventures
+- failed trades that looked profitable at purchase
+
+The model should not calculate profit from purchase price alone.
+
+---
+
+## 5. Canonical Test
+
+If the model sees:
+
+> Buy oil for 10 asses. Sell oil for 14 asses.
+
+It must ask:
+
+- what did it cost to move the oil?
+- what did storage cost?
+- were dues paid?
+- was any quantity lost?
+- how long was capital tied up?
+- what other venture was missed?
+
+Only then can total cost be known.
+
+---
+
+## 6. Success Condition
+
+If the model stops treating purchase price as total cost and starts counting every burden created by the venture, this file is functioning correctly.